power: bq24190_charger: Change first_time flag reset condition

The initial register reset of BQ24190 generates a charger status change
whose propagation via power_supply_changed is prevented using a flag.
This flag gets never reset so all following events are ignored as well
leading for example to userspace not detecting charger connects/disconnects.

Therefor change the reset condition of first_time flag, so only the
propagation of the first charger status change is prevented.

Signed-off-by: Thomas Elste <thomas.elste@imms.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>