ACPI: EC: Accelerate query execution

Split EC query handling into acknowledge and execution phase.
This allows much smaller pending query lattency and lowers chances
of EC going "wild" and losing events.

Reference: http://bugzilla.kernel.org/show_bug.cgi?id=14858



Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>