[RFC] pinctrl: ingenic: impossible MACH_* guards can drop OF match data

[Pengpeng Hou]

Hi,

while auditing conditional data-provider paths, I noticed that
drivers/pinctrl/pinctrl-ingenic.c still derives some SoC descriptor exposure
from IS_ENABLED(CONFIG_MACH_*) style conditions whose corresponding Kconfig
symbols do not appear to exist in the current Ingenic Kconfig universe.

This looks like a data-symbol legality issue rather than a simple cleanup:
the OF match table .data entries carry SoC-specific pinctrl descriptors.  If
the guard can never be true, a compatible string can lose the intended
descriptor provider even though the descriptor is still present in source.

I am not sending a patch yet because the correct policy is not obvious.  The
possible directions include:

1. remove impossible MACH_* gates from the OF match data;
2. restore current Kconfig symbols for the intended SoC families;
3. split unsupported legacy SoCs from supported descriptor exposure; or
4. keep the gates and document that these descriptors are intentionally not
   exposed.

Could you confirm which direction matches the current Ingenic pinctrl support
policy?

This is static source/Kconfig analysis only.  I have not tested the affected
hardware.

Thanks,
Pengpeng