pinctrl: sunxi: refactor pinctrl variants into flags

pinctrl: sunxi: refactor pinctrl variants into flags

For some Allwinner SoCs we have one pinctrl driver caring for multiple
very similar chips, and are tagging certain pins with a variant bitmask.
The Allwinner D1 introduced a slightly extended register layout, and we
were abusing this variant mask to convey this bit of information into
the common code part.
Now there will be more pinctrl device properties to consider (has PortF
voltage switch, for instance), so shoehorning this into the variant
bitmask will not fly anymore.

Refactor the "variant" field into a more generic "flags" field. It turns
out that we don't need the variant bits to be unique across all SoCs,
but only among those SoCs that share one driver (table), of which there
are at most three variants at the moment. So the actual variant field can
be limited to say 8 bits, and the other bits in the flag register can be
re-purposed to hold other information, like this extended register
layout.
As a side effect we can move the variant definition into the per-SoC
pinctrl driver file, which makes it more obvious that this is just a
private definition, only relevant for this particular table.
This also changes the artificial sun20i-d1 "variant" into the actual
flag bit that we are after.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/20250306235827.4895-2-andre.przywara@arm.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>