drivers/pcmcia/m32r_pcc.c: check return from request_irq

While building m32r allmodconfig we were getting warning:

  drivers/pcmcia/m32r_pcc.c:331:2: warning: ignoring return value of 'request_irq', declared with attribute warn_unused_result

request_irq() can fail and we should always be checking the result from
it. Check the result and return it to the caller.

Link: http://lkml.kernel.org/r/1474237304-897-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>