dt-bindings: reset: renesas,rst: Document r8a779a0 reset module

Document bindings for the R-Car V3U (R8A779A0) reset module.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/1599470390-29719-6-git-send-email-yoshihiro.shimoda.uh@renesas.com


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