clk: renesas: rcar-gen2: Fix PLL0 on R-Car V2H and E2

R-Car V2H and E2 do not have the PLL0CR register, but use a fixed
multiplier (depending on mode pins) and divider.

This corrects the clock rate of "pll0" (PLL0 VCO after post divider) on
R-Car V2H and E2 from 1.5 GHz to 1 GHz.

Inspired by Sergei Shtylyov's work for the common R-Car Gen2 and RZ/G
Clock Pulse Generator support core.

Fixes: 7c4163aa ("ARM: dts: r8a7792: initial SoC device tree")
Fixes: 0dce5454 ("ARM: shmobile: Initial r8a7794 SoC device tree")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>