scsi: csiostor: Mark known unused variable as __always_unused

Fixes the following W=1 kernel build warning(s):

 drivers/scsi/csiostor/csio_hw.c: In function ‘csio_hw_get_vpd_params’:
 drivers/scsi/csiostor/csio_hw.c:309:8: warning: variable ‘s’ set but not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20200723122446.1329773-22-lee.jones@linaro.org
Cc: Arkadiusz Drabczyk <arkadiusz@drabczyk.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/csiostor/csio_hw.c

@@ -306,7 +306,7 @@ csio_hw_get_vpd_params(struct csio_hw *hw, struct csio_vpd *p)
 	uint8_t *vpd, csum;
 	const struct t4_vpd_hdr *v;
 	/* To get around compilation warning from strstrip */
-	char *s;
+	char __always_unused *s;
 
 	if (csio_is_valid_vpd(hw))
 		return 0;