manifest: fix file size check in resign_image

This will allow to use size variable in < 0 checks

Signed-off-by: Adrian Bonislawski <[email protected]>

src/manifest.c

@@ -1440,7 +1440,8 @@ int resign_image(struct image *image)
 {
 	int key_size, key_file_size;
 	void *buffer = NULL;
-	size_t size, read;
+	size_t read;
+	int32_t size;
 	FILE *in_file;
 	int ret, i;