net: lan969x: add register diffs to match data

Add new file lan969x_regs.c that defines all the register differences
for lan969x, and add it to the lan969x match data.

GW_DEV2G5_PHASE_DETECTOR_CTRL, FP_DEV2G5_PHAD_CTRL_PHAD_ENA and
FP_DEV2G5_PHAD_CTRL_PHAD_FAILED are required by the new register macros
which was introduced earlier. Add these for Sparx5 also.

Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://patch.msgid.link/20241024-sparx5-lan969x-switch-driver-2-v2-7-a0b5fae88a0f@microchip.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>