drm/xe: Add documentation for Xe Device Wedging

Add documentation for Xe Device Wedging so that
file can be referenced in following patches.

Signed-off-by: Riana Tauro <[e-mail]>
Reviewed-by: Rodrigo Vivi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rodrigo Vivi <[e-mail]>

Documentation/gpu/xe/index.rst

···
    xe_tile
    xe_debugging
    xe_devcoredump
+   xe_device
    xe-drm-usage-stats.rst
    xe_configfs

Documentation/gpu/xe/xe_device.rst

···
+.. SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+
+.. _xe-device-wedging:
+
+==================
+Xe Device Wedging
+==================
+
+.. kernel-doc:: drivers/gpu/drm/xe/xe_device.c
+   :doc: Xe Device Wedging

drivers/gpu/drm/xe/xe_device.c

···
 }
 
 /**
+ * DOC: Xe Device Wedging
+ *
+ * Xe driver uses drm device wedged uevent as documented in Documentation/gpu/drm-uapi.rst.
+ * When device is in wedged state, every IOCTL will be blocked and GT cannot be
+ * used. Certain critical errors like gt reset failure, firmware failures can cause
+ * the device to be wedged. The default recovery method for a wedged state
+ * is rebind/bus-reset.
+ */
+
+/**
  * xe_device_declare_wedged - Declare device wedged
  * @xe: xe device instance
  *