AR8031 and AR8035 have the same PHY ID mask of 0xffffffef.

So fix it and make it match with the PHY ID mask definition
at drivers/net/phy/at803x.c.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>