ACPI: delete dedicated MAINTAINERS entries for ACPI EC and BATTERY drivers

We thank Alexey Starikovskiy for his significant contributions
not only to the ACPI EC and battery code, but for his profound
positive impact on the ACPICA core itself.

Alexey is busy with new challenges now, and so we'll take his
name out of MAINTAINERS to reflect that the EC and battery
are once again maintained as part part of the general ACPI
sub-system without a dedicated sub-maintainer.

Signed-off-by: Len Brown <len.brown@intel.com>