Introduce _edp_panel_vdd_on() that returns true if the call enabled vdd,
and a matching disable is needed. Keep edp_panel_vdd_on() as a helper
for when it is expected the vdd is off.
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>