uspace: compensate for kernel API breakage
uspace: compensate for kernel API breakage

Kernel 3.12 (accidentally?) renamed the sysfs file from "enable" to "enabled".
Work with either variant.

Signed-off-by: Jeff Epler <623a871f32baaca066adfe0cac08d7aa7d34027d@unpythonic.net>

ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,ikcalB/linuxcnc-mirror