This can help to reduce source code differences between Linux and ACPICA
upstream. Further driver cleanups also require these APIs to eliminate GPE
storms.
1. acpi_set_gpe(): An API that driver should invoke in the case it wants
                   to disable/enable IRQ without honoring the reference
                   count implemented in the acpi_disable_gpe() and
                   acpi_enable_gpe(). Note that this API should only be
                   invoked inside a acpi_enable_gpe()/acpi_disable_gpe()
                   pair.
2. acpi_finish_gpe(): Drivers returned ACPI_REENABLE_GPE unset from the
                      GPE handler should use this API instead of
                      invoking acpi_set_gpe()/acpi_enable_gpe() to
                      re-enable the GPE.
The GPE APIs can be invoked inside of a GPE handler or in the task context
with a driver provided lock held. This driver provided lock is safe to be
held in the GPE handler by the driver.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>