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 <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/platform/x86/msi-wmi.c

···
 	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;