clk: renesas: r8a779g0: Add MSIOF clocks

Add the module clocks used by the Clock-Synchronized Serial Interfaces
with FIFO (MSIOF) on the Renesas R-Car V4H (R8A779G0) SoC.

Extracted from a larger patch in the BSP by Kazuya Mizuguchi.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/3cb2f1798145099a46134862c6bcbdcc29ca7410.1664204336.git.geert+renesas@glider.be