power: supply: wilco_ec: Add long life charging mode

This is a long life mode set in the factory for extended warranty
battery, the power charging rate is customized so that battery at
work last longer.

Presently switching to a different battery charging mode is through
EC PID 0x0710 to configure the battery firmware, this operation will
be blocked by EC with failure code 0x01 when PLL mode is already
in use.

Signed-off-by: Crag Wang <crag.wang@dell.com>
Reviewed-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>