openpic: IRQ_check: search the queue a word at a time

openpic: IRQ_check: search the queue a word at a time

Search the queue more efficiently by first looking for a non-zero word,
and then using the common bit-searching function to find the bit within
the word.  It would be even nicer if bitops_ffsl() could be hooked up
to the compiler intrinsic so that bit-searching instructions could be
used, but that's another matter.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>