power: supply: Introduces bypass charging property

Adds a POWER_SUPPLY_CHARGE_TYPE_BYPASS option to the POWER_SUPPLY_PROP_CHARGE_TYPE
property to facilitate bypass charging operation.

In bypass charging operation, the charger bypasses the charging path around the
integrated converter allowing for a "smart" wall adaptor to perform the power
conversion externally.

This operational mode is critical for the USB PPS standard of power adaptors and is
becoming a common feature in modern charging ICs such as:

- BQ25980
- BQ25975
- BQ25960
- LN8000
- LN8410

Signed-off-by: Ricardo Rivera-Matos <rriveram@opensource.cirrus.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>