clk: renesas: Add r8a7793 CPG Core Clock Definitions

Add all R-Car M2-N Clock Pulse Generator Core Clock Outputs, as listed
in Table 7.2b ("List of Clocks [R-Car M2-W/M2-N]") of the R-Car Gen2
Hardware User's Manual rev. 2.00.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>