platform/x86: msi-wmi: Fix variable 'status' set but not used compiler warning

Explicitly check the status rather then relying on output.pointer staying
NULL on an error.

Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210204121931.131617-1-hdegoede@redhat.com

drivers/platform/x86/msi-wmi.c

@@ -96,6 +96,8 @@ static int msi_wmi_query_block(int instance, int *ret)
 	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
 
 	status = wmi_query_block(MSIWMI_BIOS_GUID, instance, &output);
+	if (ACPI_FAILURE(status))
+		return -EIO;
 
 	obj = output.pointer;