soc: renesas: rcar-rst: Allow WDT reset on R-Car V3U

V3U firmware misses to enable WDT resets. Because there won't be any
updates to the firmware anymore, enable that in Linux.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230419201511.31648-1-wsa+renesas@sang-engineering.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>