Merge branch 'add-support-for-pic64-hpsc-hx-mdio-controller'

Charles Perry says:

====================
Add support for PIC64-HPSC/HX MDIO controller

This series adds a driver for the two MDIO controllers of PIC64-HPSC/HX.
The hardware supports C22 and C45 but only C22 is implemented for now.

This MDIO hardware is based on a Microsemi design supported in Linux by
mdio-mscc-miim.c. However, The register interface is completely different
with pic64hpsc, hence the need for a separate driver.

The documentation recommends an input clock of 156.25MHz and a prescaler of
39, which yields an MDIO clock of 1.95MHz.

This was tested on Microchip HB1301 evalkit which has a VSC8574 and a
VSC8541. I've tested with bus frequencies of 0.6, 1.95 and 2.5 MHz.

This series also adds a PHY write barrier when disabling PHY interrupts as
discussed in: https://lore.kernel.org/acvUqDgepCIScs8M@shell.armlinux.org.uk
====================

Link: https://patch.msgid.link/20260408131821.1145334-1-charles.perry@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>