power: supply: ab8500: Enable USB and AC

The vendor code tree supplies platform data to enable he
USB charging for AB8500 and AB8500 and disable the AC
charging on the AB8505. This was missed when the driver
was submitted to the mainline kernel.

Fix this by doing what the vendor kernel does: always
register the USB charger, do not register the AC charger
on the AB8505.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>