Merge branch 'add-support-for-open-alliance-10base-t1x-macphy-serial-interface'

Parthiban Veerasooran says:

====================
Add support for OPEN Alliance 10BASE-T1x MACPHY Serial Interface

This patch series contain the below updates,

- Adds support for OPEN Alliance 10BASE-T1x MACPHY Serial Interface
  in the net/ethernet/oa_tc6.c.

  Link to the spec:
  -----------------
  https://opensig.org/download/document/OPEN_Alliance_10BASET1x_MAC-PHY_Serial_Interface_V1.1.pdf

- Adds driver support for Microchip LAN8650/1 Rev.B1 10BASE-T1S MACPHY
  Ethernet driver in the net/ethernet/microchip/lan865x/lan865x.c.

  Link to the product:
  --------------------
  https://www.microchip.com/en-us/product/lan8650

Testing Details:
----------------
The driver performance was tested using iperf3 in the below two setups
separately.

Setup 1:
--------
Node 0 - Raspberry Pi 4 with LAN8650 MAC-PHY
Node 1 - Raspberry Pi 4 with EVB-LAN8670-USB USB Stick

Setup 2:
--------
Node 0 - SAMA7G54-EK with LAN8650 MAC-PHY
Node 1 - Raspberry Pi 4 with EVB-LAN8670-USB USB Stick

Achieved maximum of 9.4 Mbps.

Some systems like Raspberry Pi 4 need performance mode enabled to get the
proper clock speed for SPI. Refer below link for more details.

https://github.com/raspberrypi/linux/issues/3381#issuecomment-1144723750
====================

Link: https://patch.msgid.link/20240909082514.262942-1-Parthiban.Veerasooran@microchip.com


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