clk: renesas: r8a779h0: Model PLL1/2/3/4/6 as fractional PLLs

Currently, all PLLs are modelled as fixed divider clocks, based on the
state of the mode pins.  However, the boot loader stack may have changed
the actual PLL configuration from the default, leading to incorrect
clock frequencies.

Describe PLL1 as a fixed fractional PLL instead, and PLL2, PLL3, PLL4,
and PLL6 as variable fractional PLLs.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/3beac7c44534ed153ce7cea5c31f4b0bb7b16ab0.1721648548.git.geert+renesas@glider.be