The rk3566 dwc3 otg port clock is unavailable at boot, as it defaults to
the combophy as the clock source. As combophy0 doesn't exist on rk3566,
we need to set the clock source to the usb2 phy instead.

Add handling to the grf driver to handle this on boot.
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Link: https://lore.kernel.org/r/20220408151237.3165046-3-pgwipeout@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>