net: fsl_enetc: fix imdio register calculation

net: fsl_enetc: fix imdio register calculation

With commit cc4e8af2c552, fsl_enetc register accessors have been split to
handle different register offsets on different SoCs. However, for
internal MDIO register calculation, only ENETC_PM_IMDIO_BASE was fixed
without adding the SoC specific MAC register offset.

As a result, the network support for the Kontron SMARC-sAL28 and
probably other boards based on the LS1028A CPU is broken.

Add the SoC specific MAC register offset to calculation of imdio.priv to
fix this.

Fixes: cc4e8af2c552 ("net: fsl_enetc: Split register accessors")
Signed-off-by: Thomas Schaefer <thomas.schaefer@kontron.com>
Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> # LS1028A
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx95_19x19_evk
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Alice Guo <alice.guo@nxp.com>