stmmac: intel: add pcs-xpcs for Intel mGbE controller

commit b01f855979e8880adb8daeedf39922d9ab1e4ffc from
https://source.codeaurora.org/external/autobsps32/linux



Intel mGbE controller such as those in EHL & TGL uses pcs-xpcs driver for
SGMII interface. To ensure mdio bus scanning does not assign phy_device
to MDIO-addressable entities like intel serdes and pcs-xpcs, we set up
to phy_mask to skip them.

Issue: ALB-8243
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 7310fe53)
Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Signed-off-by: Zhantao Tang <zhantao.tang@windriver.com>