ACPI: EC: Rearrange code in acpi_ec_submit_event()

Rearange acpi_ec_event_handler() so as to avoid releasing ec->lock
and acquiring it again right away in the case when ec_event_clearing
is not ACPI_EC_EVT_TIMING_EVENT.

This also reduces the number of checks done by acpi_ec_event_handler()
in that case.

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