xfs: Fix missing xfs_iunlock() on error recovery path in xfs_readlink()

Commit b52a360b forgot to call xfs_iunlock() when it detected corrupted
symplink and bailed out. Fix it by jumping to 'out' instead of doing return.

CC: stable@kernel.org
CC: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NAlex Elder <elder@kernel.org>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com> 

fs/xfs/xfs_vnodeops.c

@@ -131,7 +131,8 @@ xfs_readlink(
 			 __func__, (unsigned long long) ip->i_ino,
 			 (long long) pathlen);
 		ASSERT(0);
-		return XFS_ERROR(EFSCORRUPTED);
+		error = XFS_ERROR(EFSCORRUPTED);
+		goto out;
 	}