ACPICA: Remove extraneous check for null walk_state

ACPICA commit f9fd6e8bad0f16ce2b436c5cda36ced0c2d85302

Reported by Markus Elfring.

Link: https://github.com/acpica/acpica/commit/f9fd6e8b
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/dsmethod.c

@@ -582,9 +582,7 @@ acpi_ds_call_control_method(struct acpi_thread_state *thread,
 	/* On error, we must terminate the method properly */
 
 	acpi_ds_terminate_control_method(obj_desc, next_walk_state);
-	if (next_walk_state) {
-		acpi_ds_delete_walk_state(next_walk_state);
-	}
+	acpi_ds_delete_walk_state(next_walk_state);
 
 	return_ACPI_STATUS(status);
 }