phy: rcar-gen3-usb2: add binding for r8a77995

This patch adds binding for r8a77995 (R-Car D3). Since r8a77995 doesn't
have dedicated pins (ID, VBUS), this will match against the generic
fallback on R-Car D3.

For now, this driver doesn't support usb role swap for r8a77995.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>