ACPI: battery: Drop redundant checks from acpi_battery_remove()

ACPI: battery: Drop redundant checks from acpi_battery_remove()

In acpi_battery_remove(), "battery" cannot be NULL because it is the
driver data of the platform device passed to that function and it has
been set by acpi_battery_probe(), so drop the redundant check of it
against NULL.

Moreover, getting the ACPI device pointer from battery->device is
slightly less overhead than using the ACPI_COMPANION() macro on the
platform device to retrieve it, so do that and drop the check of that
pointer against NULL which is also redundant.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/12836976.O9o76ZdvQC@rafael.j.wysocki