[TIPC]: Fix semaphore handling.

As noted by Kevin, tipc's release() does down_interruptible() and
ignores the return value.  So if signal_pending() we'll end up doing
up() on a non-downed semaphore.  Fix.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>