More ACPI updates for v4.8-rc1 - An ACPI EC driver fix from the 4.3 cycle may cause the ACPICA's method reentrancy limit to be exceeded for a _Qxx method due to a large number of concurrent EC operations, so prevent that from happening by moving the EC handling into a separate workqueue with a limit on the number of concurrently executed work items (Lv Zheng). - Fix the cleanup code in the ACPI button driver that forgets to clear two variables on exit which causes an error to occur on the next attmpt to load the driver (Benjamin Tissoires).