pinctrl: renesas: r8a77951: Add R8A774E1 PFC support

Renesas RZ/G2H (r8a774e1) is pin compatible with R-Car H3 (r8a77951),
however it doesn't have several automotive specific peripherals. Add
a r8a77951 specific pin groups/functions along with common pin
groups/functions for supporting both r8a77951 and r8a774e1 SoC.

PFC changes are synced from mainline linux-5.9 commit
bbf5c979011a ("Linux 5.9").

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>