power: supply: bq24190_charger: Export 5V boost converter as regulator

Register the 5V boost converter as a regulator named "usb_otg_vbus".

This commit also adds support for bq24190_platform_data, through which
non device-tree platforms can pass the regulator_init_data (containing
mappings for the consumer amongst other things).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>