ACPI: EC: Use proper handle for boot EC

Fall back to ACPI_ROOT_HANDLE only in case of error.

ACPI: EC: EC description table is found, configuring boot EC
ACPI Error (evregion-0316): No handler for Region [ECOR] (ffff81007a651620) [EmbeddedControl] [20070126]
ACPI Error (exfldio-0289): Region EmbeddedControl(3) has no handler [20070126]

http://bugzilla.kernel.org/show_bug.cgi?id=9916

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

drivers/acpi/ec.c

@@ -943,7 +943,11 @@ int __init acpi_ec_ecdt_probe(void)
 		boot_ec->command_addr = ecdt_ptr->control.address;
 		boot_ec->data_addr = ecdt_ptr->data.address;
 		boot_ec->gpe = ecdt_ptr->gpe;
-		boot_ec->handle = ACPI_ROOT_OBJECT;
+		if (ACPI_FAILURE(acpi_get_handle(NULL, ecdt_ptr->id,
+				&boot_ec->handle))) {
+			pr_info("Failed to locate handle for boot EC\n");
+			boot_ec->handle = ACPI_ROOT_OBJECT;
+		}
 	} else {
 		/* This workaround is needed only on some broken machines,
 		 * which require early EC, but fail to provide ECDT */