tools: env: shift optind arguments and fix argument indices

Signed-off-by: Andreas Fenkart <andreas.fenkart@digitalstrom.com>
diff --git a/tools/env/fw_env_main.c b/tools/env/fw_env_main.c
index b68f1bf..daf4688 100644
--- a/tools/env/fw_env_main.c
+++ b/tools/env/fw_env_main.c
@@ -182,6 +182,10 @@
 		exit(EXIT_FAILURE);
 	}
 
+	/* shift parsed flags, jump to non-option arguments */
+	argc -= optind;
+	argv += optind;
+
 	lockfd = open(lockname, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 	if (-1 == lockfd) {
 		fprintf(stderr, "Error opening lock file %s\n", lockname);