drm/amdgpu/gfx6: properly cache mc_arb_ramcfg

commit 6653ebd4 upstream.

This was missing for gfx6.
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/amd/amdgpu/gfx_v6_0.c

@@ -1685,7 +1685,8 @@ static void gfx_v6_0_gpu_init(struct amdgpu_device *adev)
 	WREG32(mmBIF_FB_EN, BIF_FB_EN__FB_READ_EN_MASK | BIF_FB_EN__FB_WRITE_EN_MASK);
 
 	mc_shared_chmap = RREG32(mmMC_SHARED_CHMAP);
-	mc_arb_ramcfg = RREG32(mmMC_ARB_RAMCFG);
+	adev->gfx.config.mc_arb_ramcfg = RREG32(mmMC_ARB_RAMCFG);
+	mc_arb_ramcfg = adev->gfx.config.mc_arb_ramcfg;
 
 	adev->gfx.config.num_tile_pipes = adev->gfx.config.max_tile_pipes;
 	adev->gfx.config.mem_max_burst_length_bytes = 256;