linux-imx

mii: Add helpers for parsing SGMII auto-negotiation

Typically a MAC PCS auto-configures itself after it receives the
negotiated link settings from the PHY, but some MAC devices are more
special and need manual manipulation of the SGMII AN result.

Therefore, add the bit definitions for the SGMII registers 4 and 5
(local device ability, link partner ability), as well as a link_mode
conversion helper that can be used to feed the AN results into
phy_resolve_aneg_linkmode.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>