CIFS: Remove pointless variable assignment in cifs_dfs_do_automount()

In fs/cifs/cifs_dfs_ref.c::cifs_dfs_do_automount() we have this code:

	...
	mnt = ERR_PTR(-EINVAL);
	if (IS_ERR(tlink)) {
		mnt = ERR_CAST(tlink);
		goto free_full_path;
	}
	ses = tlink_tcon(tlink)->ses;

	rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls,
		&num_referrals, &referrals,
		cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR);

	cifs_put_tlink(tlink);

	mnt = ERR_PTR(-ENOENT);
	...

The assignment of 'mnt = ERR_PTR(-EINVAL);' is completely pointless. If we
take the 'if (IS_ERR(tlink))' branch we'll set 'mnt' again and we'll also
do so if we do not take the branch. There is no way we'll ever use 'mnt'
with the assigned 'ERR_PTR(-EINVAL)' value, so we may as well just remove
the pointless assignment.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Steve French <sfrench@us.ibm.com>