Merge branch 'net-dsa-b53-fix-rgmii-ports'

Jonas Gorski says:

====================
net: dsa: b53: fix RGMII ports

RGMII ports on BCM63xx were not really working, especially with PHYs
that support EEE and are capable of configuring their own RGMII delays.

So let's make them work, and fix additional minor rgmii related issues
found while working on it.

With a BCM96328BU-P300:

Before:

[    3.580000] b53-switch 10700000.switch GbE3 (uninitialized): validation of rgmii with support 0000000,00000000,00000000,000062ff and advertisement 0000000,00000000,00000000,000062ff failed: -EINVAL
[    3.600000] b53-switch 10700000.switch GbE3 (uninitialized): failed to connect to PHY: -EINVAL
[    3.610000] b53-switch 10700000.switch GbE3 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 4
[    3.620000] b53-switch 10700000.switch GbE1 (uninitialized): validation of rgmii with support 0000000,00000000,00000000,000062ff and advertisement 0000000,00000000,00000000,000062ff failed: -EINVAL
[    3.640000] b53-switch 10700000.switch GbE1 (uninitialized): failed to connect to PHY: -EINVAL
[    3.650000] b53-switch 10700000.switch GbE1 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 5
[    3.660000] b53-switch 10700000.switch GbE4 (uninitialized): validation of rgmii with support 0000000,00000000,00000000,000062ff and advertisement 0000000,00000000,00000000,000062ff failed: -EINVAL
[    3.680000] b53-switch 10700000.switch GbE4 (uninitialized): failed to connect to PHY: -EINVAL
[    3.690000] b53-switch 10700000.switch GbE4 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 6
[    3.700000] b53-switch 10700000.switch GbE5 (uninitialized): validation of rgmii with support 0000000,00000000,00000000,000062ff and advertisement 0000000,00000000,00000000,000062ff failed: -EINVAL
[    3.720000] b53-switch 10700000.switch GbE5 (uninitialized): failed to connect to PHY: -EINVAL
[    3.730000] b53-switch 10700000.switch GbE5 (uninitialized): error -22 setting up PHY for tree 0, switch 0, port 7

After:

[    3.700000] b53-switch 10700000.switch GbE3 (uninitialized): PHY [mdio_mux-0.1:00] driver [Broadcom BCM54612E] (irq=POLL)
[    3.770000] b53-switch 10700000.switch GbE1 (uninitialized): PHY [mdio_mux-0.1:01] driver [Broadcom BCM54612E] (irq=POLL)
[    3.850000] b53-switch 10700000.switch GbE4 (uninitialized): PHY [mdio_mux-0.1:18] driver [Broadcom BCM54612E] (irq=POLL)
[    3.920000] b53-switch 10700000.switch GbE5 (uninitialized): PHY [mdio_mux-0.1:19] driver [Broadcom BCM54612E] (irq=POLL)
====================

Link: https://patch.msgid.link/20250602193953.1010487-1-jonas.gorski@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>