tools/btmgmt: Add --limited-discov option to add-adv
tools/btmgmt: Add --limited-discov option to add-adv

This patch adds the --limited-discov (-l) option to the add-adv command,
which can be used to add "limited discoverable" advertising instances.

silent-snowman/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,silent-snowman/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,pkarasev3/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pkarasev3/bluez,mapfau/bluez,mapfau/bluez,mapfau/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,ComputeCycles/bluez,silent-snowman/bluez