dt-bindings: phy: renesas,usb2-phy: Document RZ/V2L phy bindings

Document USB phy bindings for RZ/V2L SoC. RZ/V2L USB phy is identical to
one found on the RZ/G2L SoC. No driver changes are required as generic
compatible string "renesas,rzg2l-usb2-phy" will be used as a fallback.

While at it, drop the comment "RZ/G2L family" for "renesas,rzg2l-usb2-phy"
compatible string as this will avoid changing the line for every new SoC
addition.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20220301124255.16836-1-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>