Improvements to the xpp tool dahdi_registration:
* Use the new xpp driver with support for dahdi_registration sysfs
attribute in each device.
* Wait for UDEV to finish handling span assignments (via
dahdi_waitfor_span_assignments).
* Still supports legacy drivers without this, by falling back
to old style iterative "registration" on each xpd.
Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
ca09f327ed