Some of the card callbacks needed maintstat set when processing loopup codes
from the remote side. This change is a modification of commit: (6c02c3c
"dahdi-base: Minor maint mode error")
Without this change cetain cards would not properly process the loopup /
loopdown codes (I know I should have more specific information here but the
details escape me at the moment).
Signed-off-by: Shaun Ruffell <sruffell@digium.com>