net: phy: nxp-c45-tja11xx: prepare the ground for TJA1120

Between TJA1120 and TJA1103 the hardware was improved, but some register
addresses were changed and some bit fields were moved from one register
to another.

Introduce the nxp_c45_reg_field structure and its associated functions to
abstract the differences between the PHYs.

Remove the defined bits and register addresses that are not common
between TJA1103 and TJA1120 and replace them with reg_fields and
register addresses from phydev->drv->driver_data.

Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Link: https://lore.kernel.org/r/20230731091619.77961-4-radu-nicolae.pirea@oss.nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>