[SCSI] bfa: set correct command return code

For various error conditions the bfa driver just returns
'DID_ERROR', which carries no information at all about the
actual source of error.
This patch updates the error handling to return a correct
error code, depending on the type of error occurred.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Acked-by: Vijaya Mohan Guvva <vmohan@brocade.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>