reset: renesas: Add RZ/G2L usbphy control driver

Add support for RZ/G2L USBPHY Control driver. It mainly controls
reset and power down of the USB/PHY.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20210719121938.6532-5-biju.das.jz@bp.renesas.com
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>