raiden_debug_spi: Fix memleak

Change-Id: Ib9d99fefda812d20265db47be353c844f8b77129
Found-by: Coverity Scan #1420204
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/40969


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

raiden_debug_spi.c

@@ -480,8 +480,10 @@ int raiden_debug_spi_init(void)
 	int ret;
 
 	int request_enable = get_target();
-	if (request_enable < 0)
+	if (request_enable < 0) {
+		free(serial);
 		return 1;
+	}
 
 	usb_match_init(&match);