power_supply: lp8788-charger: initialize boolean 'found'

The boolean 'found' is not initialized and hence garbage. It should
be initialized as false.

Found with static analysis using CoverityScan

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Milo Kim <milo.kim@ti.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>