ACPI: battery: Simplify battery hook locking

Move the conditional locking from __battery_hook_unregister()
into battery_hook_unregister() and rename the low-level function
to simplify the locking during battery hook removal.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/20241001212835.341788-2-W_Armin@gmx.de


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>