sh-sci: document R8A7743/5 support

Renesas RZ/G SoC also have the SCIF, SCIFA, SCIFB, and HSCIF ports and
they  seem compatible with the R-Car gen2 SoC  in this respect...
Document RZ/G1[ME] (also known as R8A774[35]) SoC bindings.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>