There are three major variants of the AXP PMIC GPIO functionality (plus
PMICs with no GPIOs at all). Except for GPIO3 on the AXP209, which uses
a different register layout, it is straightforward to support all three
variants with a single driver. Do this, and in the process remove the
GPIO-related definitions from the PMIC-specific headers, and therefore
the dependency on AXP_PMIC_BUS.
Signed-off-by: Samuel Holland <samuel@sholland.org>
a3a6dde671