drm/amdkfd: Group up CRAT related functions

Take CRAT related functions out of kfd_topology.c and place them in
kfd_crat.c. This is the initial step of supporting more CRAT features,
i.e. creating virtual CRAT table for KFD devices without CRAT.

v2: Minor cleanup that was missed previously because code moved around

Signed-off-by: Amber Lin <Amber.Lin@amd.com>
Signed-off-by: Kent Russell <kent.russell@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>