clk: renesas: r8a77965: Add RPC clocks

Describe the RPCSRC internal clock and the RPC[D2] clocks derived from
it, as well as the RPC-IF module clock, in the R-Car M3-N (R8A77965)
CPG/MSSR driver.

Inspired by commit 94e3935b ("clk: renesas: r8a77980: Add RPC clocks").

Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Link: https://lore.kernel.org/r/20200203072901.31548-3-dirk.behme@de.bosch.com


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