power: supply: smb347-charger: Improve interrupt initialization

A previous commit attempted to fix IRQ usage in a case where interrupt
is failed to initialize, but it missed couple more cases that could be
improved. The interrupt could be undefined and then everything related
to interrupt shouldn't be touched by driver. Secondly, we shouldn't ignore
errors that aren't directly related to enabling interrupt in hardware,
like enabling h/w write-access or requesting interrupt. Improve interrupt
initialization in the driver in order to handle the missing cases.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>