i915: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: Zhenyu Wang <[email protected]>
Cc: Zhi Wang <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Rodrigo Vivi <[email protected]>
Reviewed-by: Zhenyu Wang <[email protected]>
Signed-off-by: Zhenyu Wang <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: gregkh

drivers/gpu/drm/i915/gvt/kvmgt.c

@@ -699,7 +699,7 @@ static void intel_vgpu_close_device(struct vfio_device *vfio_dev)
 
 	clear_bit(INTEL_VGPU_STATUS_ATTACHED, vgpu->status);
 
-	debugfs_remove(debugfs_lookup(KVMGT_DEBUGFS_FILENAME, vgpu->debugfs));
+	debugfs_lookup_and_remove(KVMGT_DEBUGFS_FILENAME, vgpu->debugfs);
 
 	kvm_page_track_unregister_notifier(vgpu->vfio_device.kvm,
 					   &vgpu->track_node);