HID: input: rename hidinput_set_battery_charge_status()

In preparation for a patch fixing a bug affecting
hidinput_set_battery_charge_status(), rename the function to
hidinput_update_battery_charge_status() and move it up so it can be used
by hidinput_update_battery().

Refactor, no functional changes.

Tested-by: 卢国宏 <luguohong@xiaomi.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>