[SCSI] bfa: fix endian and bit field check bug

Fix some endian issue. __BIGENDIAN is not defined and it needs to be
replaced with __BIG_ENDIAN. Also fixed a bug in bit field access.
These two issues were reported by Dan Carpenter.

Signed-off-by: Jing Huang <huangj@brocade.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>