power: supply: qcom_battmgr: support disabling charge control

power: supply: qcom_battmgr: support disabling charge control

Existing userspace (in particular, upower) disables charge control by
setting the start threshold to 0 and the stop threshold to 100.

Handle that by actually setting the enable bit to 0 when a start
threshold of 0 was requested.

Fixes: cc3e883a0625 ("power: supply: qcom_battmgr: Add charge control support")
Signed-off-by: Val Packett <val@packett.cool>
Link: https://patch.msgid.link/20251012233333.19144-4-val@packett.cool
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>