power: supply: core: Add type property to uevent env

Add POWER_SUPPLY_TYPE to the uevent env for power supply. Type is a
property of all power supplies and there is a sysfs entry for it but it
is not included in the properties array of the power supply so
explicitly add it to the udev env.

Signed-off-by: Mathew King <mathewk@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>