drm/vgem/vgem_drv: Standard comment blocks should not use kernel-doc format

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/vgem/vgem_drv.c:47: warning: expecting prototype for This is vgem, a (non-hardware(). Prototype was for DRIVER_NAME() instead

Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: Adam Jackson <ajax@redhat.com>
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210526084726.552052-31-lee.jones@linaro.org

drivers/gpu/drm/vgem/vgem_drv.c

@@ -25,7 +25,7 @@
  *	Ben Widawsky <ben@bwidawsk.net>
  */
 
-/**
+/*
  * This is vgem, a (non-hardware-backed) GEM service.  This is used by Mesa's
  * software renderer and the X server for efficient buffer sharing.
  */