[SCSI] esas2r: smatch - Fix dereference that occurs prior to check

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Bradley Grove <bgrove@attotech.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/esas2r/esas2r_flash.c b/drivers/scsi/esas2r/esas2r_flash.c
index 8582929..45e353f 100644
--- a/drivers/scsi/esas2r/esas2r_flash.c
+++ b/drivers/scsi/esas2r/esas2r_flash.c
@@ -860,8 +860,13 @@
 		return false;
 	}
 
+	if (fsc->command >= cmdcnt) {
+		fs->status = ATTO_STS_INV_FUNC;
+		return false;
+	}
+
 	func = cmd_to_fls_func[fsc->command];
-	if (fsc->command >= cmdcnt || func == 0xFF) {
+	if (func == 0xFF) {
 		fs->status = ATTO_STS_INV_FUNC;
 		return false;
 	}