phy: renesas: phy-rcar-gen2: Add support for r8a77470

This patch adds support for RZ/G1C (r8a77470) SoC. RZ/G1C SoC has a
PLL register shared between hsusb0 and hsusb1. Compared to other RZ/G1
and R-Car Gen2/3, USB Host needs to deassert the pll reset.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-and-Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>