amdkfd: properly free secondary context id

amdkfd: properly free secondary context id

Function kfd_process_free_id() should skip over
the primary kfd process because its context id
is fixed assigned, not allocated through the ida table.
This function should only work on secondary contexts.

Fixes: fac682a1d1af ("amdkfd: identify a secondary kfd process by its id")
Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>