scsi: remove private BIT macros

A couple of scsi drivers define a BIT() macro, duplicating the one in
bitops.h.

Cc: Jing Huang <huangj@brocade.com>
Cc: Robert Love <robert.w.love@intel.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>