Merge branch 'initial-support-for-pic64-hpsc-hx-ethernet-endpoint'

Merge branch 'initial-support-for-pic64-hpsc-hx-ethernet-endpoint'

Charles Perry says:

====================
Initial support for PIC64-HPSC/HX Ethernet endpoint

This series add basic support for Microchip "PIC64-HPSC" and "PIC64HX"
Ethernet endpoint. Both SoCs contain 4 GEM IP with support for
MII/RGMII/SGMII/USXGMII at rates of 10M to 10G. Only RGMII and SGMII at a
rate of 1G is tested for now. Each GEM IP has 8 priority queues and the
revision register reads 0x220c010e.

One particularity of this instantiation of GEM is that the MDIO controller
within the GEM IP is disconnected from any physical pin and the SoC rely on
another standalone MDIO controller.

The maximum jumbo frame size also seems to be different on PIC64-HPSC/HX
(16383) than what most other platforms use (10240). I've found that I need
to tweak a bit the MTU calculation for this, otherwise the RXBS field of
the DMACFG register overflows. See patch 2 for more details.

PIC64-HPSC/HX also supports other features guarded behind CAPS bit like
MACB_CAPS_QBV but I've omitted those intentionally because I didn't test
these.
====================

Link: https://patch.msgid.link/20260313140610.3681752-1-charles.perry@microchip.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>