net: stmmac: dwmac-rk: Validate GRF and peripheral GRF during probe

All Rockchip GMAC variants typically write to GRF regs to control e.g.
interface mode, speed and MAC rx/tx delay. Newer SoCs such as RK3576 and
RK3588 use a mix of GRF and peripheral GRF regs. These syscon regmaps is
located with help of a rockchip,grf and rockchip,php-grf phandle.

However, validating the rockchip,grf and rockchip,php-grf syscon regmap
is deferred until e.g. interface mode or speed is configured, inside the
individual SoC specific operations.

Change to validate the rockchip,grf and rockchip,php-grf syscon regmap
at probe time to simplify all SoC specific operations.

This should not introduce any backward compatibility issues as all
GMAC nodes have been added together with a rockchip,grf phandle (and
rockchip,php-grf where required) in their initial commit.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250308213720.2517944-3-jonas@kwiboo.se


Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>