ext4: fix typo which broke '..' detection in ext4_find_entry()

There should be a check for the NUL character instead of '0'.

Fortunately the only thing that cares about this is NFS serving, which
is why we didn't notice this in the merge window testing.
Reported-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/namei.c

@@ -872,7 +872,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
 	if (namelen > EXT4_NAME_LEN)
 		return NULL;
 	if ((namelen <= 2) && (name[0] == '.') &&
-	    (name[1] == '.' || name[1] == '0')) {
+	    (name[1] == '.' || name[1] == '\0')) {
 		/*
 		 * "." or ".." will only be in the first block
 		 * NFS may look up ".."; "." should be handled by the VFS