sunxi: axp: Generalize register macros for VBUS drive GPIO

VBUS drive is supported on AXP221 and later PMICs. Rework the macros
so we can support this on later PMICs without too much work.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>