phy: rockchip: inno-usb2: Simplify rockchip,usbgrf handling

phy: rockchip: inno-usb2: Simplify rockchip,usbgrf handling

The logic to decide if usbgrf or grf should be used is more complex than
it needs to be. For RK3568, RV1108 and soon RK3528 we can assign the
rockchip,usbgrf regmap directly to grf instead of doing a usbgrf and grf
dance.

Simplify the code to only use the grf regmap and handle the logic of
what regmap should be used in driver probe instead.

The only expected change from this is that RK3528 can be supported
because of an addition of a of_property_present() check.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260505170410.3265305-3-heiko@sntech.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>