ext4: silence a format string false positive

Static checkers complain that the format string should be "%s".  It does
not make a difference for the current code.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mmp.c

@@ -115,7 +115,7 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
 void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
 		    const char *function, unsigned int line, const char *msg)
 {
-	__ext4_warning(sb, function, line, msg);
+	__ext4_warning(sb, function, line, "%s", msg);
 	__ext4_warning(sb, function, line,
 		       "MMP failure info: last update time: %llu, last update "
 		       "node: %s, last update device: %s\n",