sunxi: axp221: Add support for controlling the drivebus pin

The axp221 / axp223's N_VBUSEN pin can be configured as an output rather
then an input, add axp_drivebus_enable() and _disable() functions to set
the pin in output mode and control it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
2 files changed