scsi: ufs: Fix the build for the old ARM OABI

All structs and unions are word aligned when using the OABI. Mark the union
in struct utp_upiu_header as packed to prevent that the compiler inserts
padding bytes.

Cc: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202308251634.tuRn4OVv-lkp@intel.com/
Fixes: 617bfaa ("scsi: ufs: Simplify response header parsing")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230829163547.1200183-1-bvanassche@acm.org
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

include/uapi/scsi/scsi_bsg_ufs.h

@@ -83,7 +83,7 @@ struct utp_upiu_header {
 			union {
 				__u8 tm_function;
 				__u8 query_function;
-			};
+			} __attribute__((packed));
 			__u8 response;
 			__u8 status;
 			__u8 ehs_length;