smb: client: fix copy-paste error in WSL EA length accounting for $LXDEV

The LXDEV block in cifs_query_path_info() uses SMB2_WSL_XATTR_MODE_SIZE
(4) instead of SMB2_WSL_XATTR_DEV_SIZE (8), undercounting eas_len by 4
bytes per $LXDEV EA.

eas_len is used only as a zero/non-zero presence flag so there is no
current functional impact, but the value is incorrect and misleading.

Fixes: 97db41604555 ("smb: client: parse uid, gid, mode and dev from WSL reparse points")
Cc: stable@vger.kernel.org
Cc: Paulo Alcantara <pc@manguebit.org>
Signed-off-by: Frank Sorenson <sorenson@redhat.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>