mxm/wmi: add MXMX interface entry point.

The MXMX method appears to be a mutex of some sort.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/linux/mxm-wmi.h b/include/linux/mxm-wmi.h
index 51359c0..617a295 100644
--- a/include/linux/mxm-wmi.h
+++ b/include/linux/mxm-wmi.h
@@ -27,6 +27,7 @@
 /* integrated adapter */
 #define MXM_MXDS_ADAPTER_IGD 0x10
 int mxm_wmi_call_mxds(int adapter);
+int mxm_wmi_call_mxmx(int adapter);
 bool mxm_wmi_supported(void);
 
 #endif