scsi: pm8001: Replace one-element array with flexible-array member

One-element arrays are deprecated, and we are replacing them with flexible
array members instead. So, replace one-element array with flexible-array
member in struct fw_control_info.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines
on memcpy() and help us make progress towards globally enabling
-fstrict-flex-arrays=3 [1].

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/207
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 [1]
Link: https://lore.kernel.org/r/Yyy31OuBza1FJCXP@workReviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NJack Wang <jinpu.wang@ionos.com>
Signed-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/pm8001/pm8001_sas.h

@@ -612,7 +612,7 @@ struct fw_control_info {
 	operations.*/
 	u32			reserved;/* padding required for 64 bit
 	alignment */
-	u8			buffer[1];/* Start of buffer */
+	u8			buffer[];/* Start of buffer */
 };
 struct fw_control_ex {
 	struct fw_control_info *fw_control;