drm/radeon: fix ATPX regression in acpi rework

Copy and paste typo in the apci rework.

Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=49351

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>

drivers/gpu/drm/radeon/radeon_atpx_handler.c

@@ -87,7 +87,7 @@ static union acpi_object *radeon_atpx_call(acpi_handle handle, int function,
 		atpx_arg_elements[1].integer.value = 0;
 	}
 
-	status = acpi_evaluate_object(handle, "ATPX", &atpx_arg, &buffer);
+	status = acpi_evaluate_object(handle, NULL, &atpx_arg, &buffer);
 
 	/* Fail only if calling the method fails and ATPX is supported */
 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {