ab8500_fg: Added support for BATT_OVV

Add support for the battery over-voltage situation

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Hakan Berg <hakan.berg@stericsson.com>
Reviewed-by: Karl KOMIEROWSKI <karl.komierowski@stericsson.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>