drm/amdkfd: Add gfx_target_version for GC 9.4.3

Required for Thunk GFX version sysfs query.

Signed-off-by: Graham Sider <Graham.Sider@amd.com>
Reviewed-by: Amber Lin <Amber.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>