isdn: cpai: no need to initialise statics to 0

Static variables do not need to be initialised to 0, because compiler
will initialise all uninitialised statics to 0. Thus, remove the
unneeded initializations.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>