scsi: bsg: Replace zero-length array with flexible array member

Replace the deprecated zero-length array with a modern flexible array
member in the struct iscsi_bsg_host_vendor_reply.

Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Thorsten Blum <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

include/scsi/scsi_bsg_iscsi.h

···
  */
 struct iscsi_bsg_host_vendor_reply {
 	/* start of vendor response area */
-	uint32_t vendor_rsp[0];
+	DECLARE_FLEX_ARRAY(uint32_t, vendor_rsp);
 };