Calling acpi_dispatch_gpe() from acpi_ec_dispatch_gpe() is generally
problematic, because it may cause the spurious interrupt handling in
advance_transaction() to trigger in theory.

However, instead of calling acpi_dispatch_gpe() to dispatch the EC
GPE, acpi_ec_dispatch_gpe() can call advance_transaction() directly
on first_ec and it can pass 'false' as its second argument to indicate
calling it from process context.

Moreover, if advance_transaction() is modified to return a bool value
indicating whether or not the EC work needs to be flushed, it can be
used to avoid unnecessary EC work flushing in acpi_ec_dispatch_gpe(),
so change the code accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>