[SCSI] sym53c416: kill pointless irq handler loop and test

- kill pointless irq handler loop to find base address, it is already
  passed to irq handler via Scsi_Host.

- kill now-pointless !base test.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>