clk: renesas: r8a779h0: Add RPC-IF clock

Add the module clock used by the SPI Multi I/O Bus Controller (RPC-IF)
on the Renesas R-Car V4M (R8A779H0) SoC.

Signed-off-by: Cong Dang <cong.dang.xn@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/07a72378ca64b44341af960f042a6efd41d10dc3.1708354355.git.geert+renesas@glider.be