drm/amdgpu/gfx10: add updated GOLDEN_TSC_COUNT_UPPER/LOWER register offsets for VGH

The address of the GOLDEN_TSC_COUNT_UPPER/GOLDEN_TSC_COUNT_LOWER for
Vnagogh are different from the others.

The offset of the GOLDEN_TSC_COUNT_UPPER for Vangogh is 0x0025 by
calculation.
The offset of the GOLDEN_TSC_COUNT_LOWER for Vangogh is 0x0026 by
calculation.

Signed-off-by: chen gong <curry.gong@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>