[SCSI] zfcp: Remove duplicated unlikely() macros.

Some drivers have duplicated unlikely() macros. IS_ERR() already
has unlikely() in itself. This patch cleans up such pointless
codes although there is no real effect on the kernel's behaviour.

Signed-off-by: Hirofumi Nakagawa <hnakagawa@miraclelinux.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>