dt-bindings: reset: renesas,rst: Document r8a779f0 reset module

Document bindings for the R-Car S4-8 (R8A779F0) reset module.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20211116074130.107554-4-yoshihiro.shimoda.uh@renesas.com


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