platform/x86: wmi: add missing struct parameter description

Add a description for the context parameter in the struct wmi_device_id.

Reported-by: kbuild test robot <lkp@intel.com>
Fixes: a48e23385f ("platform/x86: wmi: add context pointer field to struct wmi_device_id")
Signed-off-by: Mattias Jacobsson <2pi@mok.nu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

include/linux/mod_devicetable.h

@@ -814,6 +814,7 @@ struct tee_client_device_id {
 /**
  * struct wmi_device_id - WMI device identifier
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
+ * @context: pointer to driver specific data
  */
 struct wmi_device_id {
 	const char guid_string[UUID_STRING_LEN+1];