phy: renesas: rcar-gen3-usb2: Add support to initialize the bus

phy: renesas: rcar-gen3-usb2: Add support to initialize the bus

The Renesas RZ/G3S need to initialize the USB BUS before transferring data
due to hardware limitation. As the register that need to be touched for
this is in the address space of the USB PHY, and the UBS PHY need to be
initialized before any other USB drivers handling data transfer, add
support to initialize the USB BUS.

As the USB PHY is probed before any other USB drivers that enables
clocks and de-assert the reset signals and the BUS initialization is done
in the probe phase, we need to add code to de-assert reset signal and
runtime resume the device (which enables its clocks) before accessing
the registers.

As the reset signals are not required by the USB PHY driver for the other
USB PHY hardware variants, the reset signals and runtime PM was handled
only in the function that initialize the USB BUS.

The PHY initialization was done right after runtime PM enable to have
all in place when the PHYs are registered.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240822152801.602318-11-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>