power: supply: axp20x_usb_power: fix warning on 64bit

Casting of_device_get_match_data return value to int causes warning on 64bit
architectures.

../drivers/power/supply/axp20x_usb_power.c: In function
'axp20x_usb_power_probe':
../drivers/power/supply/axp20x_usb_power.c:297:21: warning: cast from
pointer to integer of different size [-Wpointer-to-int-cast]

Fixes: 0dcc70ca ("power: supply: axp20x_usb_power: use of_device_id
    data field instead of device_is_compatible")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>