fix segmentation fault when selecting PDM
fix segmentation fault when selecting PDM

If you picked PDM on Mesa page and then pressed next
pncconf would fault. This was because the ptype model
was not changed from pwm to pdm and mesa_transfer would
search for the iter in pdm model. Then rudely crashed.

bobvanderlinden/machinekit,araisrobo/machinekit,unseenlaser/machinekit,unseenlaser/machinekit,ArcEye/MK-Qt5,araisrobo/machinekit,RunningLight/machinekit,araisrobo/machinekit,EqAfrica/machinekit,ArcEye/MK-Qt5,araisrobo/machinekit,unseenlaser/machinekit,Cid427/machinekit,araisrobo/machinekit,cdsteinkuehler/linuxcnc,ArcEye/machinekit-testing,Cid427/machinekit,ikcalB/linuxcnc-mirror,ArcEye/machinekit-testing,ikcalB/linuxcnc-mirror,unseenlaser/machinekit,EqAfrica/machinekit,unseenlaser/linuxcnc,kinsamanka/machinekit,bobvanderlinden/machinekit,unseenlaser/machinekit,ArcEye/machinekit-testing,mhaberler/machinekit,unseenlaser/machinekit,strahlex/machinekit,ArcEye/MK-Qt5,kinsamanka/machinekit,cdsteinkuehler/linuxcnc,unseenlaser/linuxcnc,Cid427/machinekit,kinsamanka/machinekit,EqAfrica/machinekit,unseenlaser/machinekit,unseenlaser/machinekit,aschiffler/linuxcnc,ArcEye/machinekit-testing,aschiffler/linuxcnc,araisrobo/linuxcnc,araisrobo/linuxcnc,cnc-club/linuxcnc,unseenlaser/linuxcnc,mhaberler/machinekit,ikcalB/linuxcnc-mirror,bobvanderlinden/machinekit,mhaberler/machinekit,bobvanderlinden/machinekit,bmwiedemann/linuxcnc-mirror,Cid427/machinekit,cdsteinkuehler/MachineKit,RunningLight/machinekit,mhaberler/machinekit,RunningLight/machinekit,kinsamanka/machinekit,ArcEye/MK-Qt5,mhaberler/machinekit,bobvanderlinden/machinekit,aschiffler/linuxcnc,araisrobo/machinekit,ArcEye/machinekit-testing,cnc-club/linuxcnc,narogon/linuxcnc,narogon/linuxcnc,EqAfrica/machinekit,bmwiedemann/linuxcnc-mirror,cnc-club/linuxcnc,bmwiedemann/linuxcnc-mirror,EqAfrica/machinekit,cdsteinkuehler/MachineKit,Cid427/machinekit,cnc-club/linuxcnc,strahlex/machinekit,ArcEye/MK-Qt5,narogon/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,Cid427/machinekit,kinsamanka/machinekit,Cid427/machinekit,ianmcmahon/linuxcnc-mirror,jaguarcat79/ILC-with-LinuxCNC,narogon/linuxcnc,cnc-club/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,cdsteinkuehler/linuxcnc,RunningLight/machinekit,ArcEye/MK-Qt5,bobvanderlinden/machinekit,mhaberler/machinekit,araisrobo/linuxcnc,cnc-club/linuxcnc,bobvanderlinden/machinekit,jaguarcat79/ILC-with-LinuxCNC,kinsamanka/machinekit,kinsamanka/machinekit,ikcalB/linuxcnc-mirror,cdsteinkuehler/linuxcnc,bobvanderlinden/machinekit,RunningLight/machinekit,mhaberler/machinekit,ArcEye/machinekit-testing,strahlex/machinekit,strahlex/machinekit,ianmcmahon/linuxcnc-mirror,araisrobo/machinekit,strahlex/machinekit,ikcalB/linuxcnc-mirror,araisrobo/machinekit,strahlex/machinekit,aschiffler/linuxcnc,ArcEye/machinekit-testing,cdsteinkuehler/MachineKit,jaguarcat79/ILC-with-LinuxCNC,bmwiedemann/linuxcnc-mirror,araisrobo/linuxcnc,cnc-club/linuxcnc,ianmcmahon/linuxcnc-mirror,EqAfrica/machinekit,aschiffler/linuxcnc,RunningLight/machinekit,RunningLight/machinekit,RunningLight/machinekit,bmwiedemann/linuxcnc-mirror,kinsamanka/machinekit,EqAfrica/machinekit,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/MachineKit,ikcalB/linuxcnc-mirror,mhaberler/machinekit,ArcEye/machinekit-testing,bmwiedemann/linuxcnc-mirror,cdsteinkuehler/linuxcnc,ArcEye/MK-Qt5,ArcEye/MK-Qt5,ikcalB/linuxcnc-mirror,ianmcmahon/linuxcnc-mirror,EqAfrica/machinekit,araisrobo/machinekit,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/MachineKit,cdsteinkuehler/linuxcnc,ianmcmahon/linuxcnc-mirror,cdsteinkuehler/MachineKit,araisrobo/linuxcnc,strahlex/machinekit,narogon/linuxcnc,unseenlaser/linuxcnc,bmwiedemann/linuxcnc-mirror,unseenlaser/linuxcnc,Cid427/machinekit