power: supply: cpcap-charger: get the battery inserted infomation from cpcap-battery

This avoids reimplementing the detection logic twice and removes the
possibility of activating charging with 500mA even if a battery is not
detected.

Signed-off-by: Carl Philipp Klemm <philipp@uvos.xyz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>