power: supply: max17042_battery: Clear status bits in interrupt handler

The gauge requires us to clear the status bits manually for some alerts
to be properly dismissed. Previously the IRQ was configured to react only
on falling edge, which wasn't technically correct (the ALRT line is active
low), but it had a happy side-effect of preventing interrupt storms
on uncleared alerts from happening.

Fixes: 7fbf6b73 ("power: supply: max17042: Do not enforce (incorrect) interrupt trigger type")
Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>