drm/amdgpu: fix the incorrect scratch reg number on gfx v7

Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c

@@ -2021,7 +2021,7 @@ static void gfx_v7_0_gpu_init(struct amdgpu_device *adev)
  */
 static void gfx_v7_0_scratch_init(struct amdgpu_device *adev)
 {
-	adev->gfx.scratch.num_reg = 7;
+	adev->gfx.scratch.num_reg = 8;
 	adev->gfx.scratch.reg_base = mmSCRATCH_REG0;
 	adev->gfx.scratch.free_mask = (1u << adev->gfx.scratch.num_reg) - 1;
 }