[SCSI] wd33c93: cleanups

- #include <asm/irq.h> for getting the prototypes of {dis,en}able_irq()

- make the needlessly global wd33c93_setup() static

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>