drm/amdgpu/sdma4: drop unused register header

nbio registers are not used in this file.
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: Frank Min <Frank.Min@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c

@@ -35,7 +35,6 @@
 #include "vega10/MMHUB/mmhub_1_0_offset.h"
 #include "vega10/MMHUB/mmhub_1_0_sh_mask.h"
 #include "vega10/HDP/hdp_4_0_offset.h"
-#include "vega10/NBIO/nbio_6_1_offset.h"
 #include "raven1/SDMA0/sdma0_4_1_default.h"
 
 #include "soc15_common.h"