drm/amdgpu/gfx10: remove outdated comments

Signed-off-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Reviewed-by: Zhan Liu <zhan.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c

@@ -50,9 +50,6 @@
  * Navi10 has two graphic rings to share each graphic pipe.
  * 1. Primary ring
  * 2. Async ring
- *
- * In bring-up phase, it just used primary ring so set gfx ring number as 1 at
- * first.
  */
 #define GFX10_NUM_GFX_RINGS	2
 #define GFX10_MEC_HPD_SIZE	2048