Staging: octeon: don't ignore request_irq() return code

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>