drm/amdgpu: fix KV harvesting

Always set the graphics values to the max for the
asic type.  E.g., some 1 RB chips are actually 1 RB chips,
others are actually harvested 2 RB chips.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=99353
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org