ACPI: acpi_drivers.h: Remove the leftover dead code

After commit 5ba8b1c6 ("ACPI: remove dead code"),
ACPI_PROCESSOR_LIMIT_* macros are not used anymore, remove it.

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