drm/amdgpu: Cleanup 2 compiler warnings

These 2 variables are unused now, so remove their references.

Fixes: e4ae0fc3 drm/amdgpu: implement gfx8 post_soft_reset
Fixes: 5e01c09 drm/amdgpu/gfx_v8_0: Reorder the gfx, kiq and kcq rings
test sequence

Signed-off-by: Kent Russell <kent.russell@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>