drm/amdkfd: Fix sibling_map[] size

Change kfd_cache_properties.sibling_map[256] to
kfd_cache_properties.sibling_map[32]. Since, CRAT uses bitmap for
sibling_map, it is more efficient to use bitmap in the kfd structure
also.

Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@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>