dt-bindings: watchdog: renesas,wdt: Document RZ/V2L SoC

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

While at it, drop the comment "# RZ/G2L" for "renesas,rzg2l-wdt"
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: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220301122332.14796-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>