ACPI: EC: Re-use boot_ec when possible even when EC_FLAGS_TRUST_DSDT_GPE is set

EC_FLAGS_TRUST_DSDT_GPE only does anything when the:

	if (boot_ec && ec->command_addr == boot_ec->command_addr &&
	    ec->data_addr == boot_ec->data_addr)

conditions are all true. Normally acpi_ec_add() would re-use the boot_ec
struct acpi_ec in this case. But when the EC_FLAGS_TRUST_DSDT_GPE flag was
set the code would continue with a newly allocated (second) struct acpi_ec.

There is no reason to use a second struct acpi_ec if all the above checks
match. Instead just change boot_ec->gpe to ec->gpe, when the flag is set,
similar to how this is already one done for boot_ec->handle.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>