util/amdfwtool: Close file descriptor on error

Prevents a resource leak.

Change-Id: Id5da2df3e37cba499cd2e9a7c3ede34e4de2ed77
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Found-by: Coverity CID 1402139
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33961
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/amdfwtool/amdfwtool.c

@@ -566,11 +566,13 @@ static ssize_t copy_blob(void *dest, const char *src_file, size_t room)
 
 	if (fstat(fd, &fd_stat)) {
 		printf("fstat error: %s\n", strerror(errno));
+		close(fd);
 		return -2;
 	}
 
 	if (fd_stat.st_size > room) {
 		printf("Error: %s will not fit.  Exiting.\n", src_file);
+		close(fd);
 		return -3;
 	}