drm/amdgpu: fix the incorrect scratch reg number on gfx v8

Signed-off-by: NHuang Rui <ray.huang@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -750,7 +750,7 @@ static void gfx_v8_0_init_golden_registers(struct amdgpu_device *adev)
 
 static void gfx_v8_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;
 }