power: supply: cpcap-charger: Simplify bool conversion

Fix the following coccicheck warning:
./drivers/power/supply/cpcap-charger.c:416:31-36: WARNING: conversion to
bool not needed here

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>