net: dsa: b53: ensure BCM5325 PHYs are enabled

net: dsa: b53: ensure BCM5325 PHYs are enabled

According to the datasheet, BCM5325 uses B53_PD_MODE_CTRL_25 register to
disable clocking to individual PHYs.
Only ports 1-4 can be enabled or disabled and the datasheet is explicit
about not toggling BIT(0) since it disables the PLL power and the switch.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20250614080000.1884236-15-noltari@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>