Most clock factors and dividers in the H6 PLLs use a "+1 encoding",
which we were missing on two occasions.

This fixes the MMC clock setup on the H6, which could be slightly off due
to the wrong parent frequency:
mmc 2 set mod-clk req 52000000 parent 1176000000 n 2 m 12 rate 49000000

Also the CPU frequency (PLL1) was a tad too high before.

For PLL5 (DRAM) we already accounted for this +1, but in the DRAM code
itself, not in the bit field macro. Move this there to be aligned with
what the other SoCs and other PLLs do.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NJernej Skrabec <jernej.skrabec@gmail.com>