Revert "ACPI: battery: negate current when discharging"

Revert commit 234f7155 ("ACPI: battery: negate current when
discharging") breaks not one but several userspace implementations
of battery monitoring: Steam and MangoHud. Perhaps it breaks more,
but those are the two that have been tested.

Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Closes: https://lore.kernel.org/linux-acpi/87C1B2AF-D430-4568-B620-14B941A8ABA4@linux.dev/


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