In an Astribank with >= 2 PRI ports, switching from E1 to T1 at run-time
may fail at the DAHDI_CHANCONFIG ioctl on the first channel in a span,
That is, on first run of dahdi_cfg, it fails on second span, on second:
it fails on third span, etc.
The code clears the D-channel information on the DAHDI_CHANCONFIG call
for the first channel in the span.
However The code tested for the global "channo" rather than the per-span
"chanpos" to check for the first channel in the span. This the test
failed.
Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>