ceph: requalify some char pointers as const

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/super.c

@@ -288,7 +288,7 @@ static int ceph_parse_new_source(const char *dev_name, const char *dev_name_end,
 	struct ceph_options *opts = pctx->copts;
 	struct ceph_mount_options *fsopt = pctx->opts;
 	const char *name_start = dev_name;
-	char *fsid_start, *fs_name_start;
+	const char *fsid_start, *fs_name_start;
 
 	if (*dev_name_end != '=') {
 		dout("separator '=' missing in source");