Some max77802 LDOs (1, 3, 20 and 21) support to be configured in Low
Power Mode during system normal operation. Add function handlers for
the .get_mode and .set_mode operations to set the mode on these LDOs.
Signed-off-by: NJavier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: NMark Brown <broonie@kernel.org>