drm/amdkfd: Cleanup kfd_process if init_cwsr_apu fails

If init_cwsr_apu fails, we currently leave the kfd_process structure in
place anyway. The next kfd_open will then succeed, using the existing
kfd_process structure. Fix that by cleaning up the kfd_process after a
failure in init_cwsr_apu.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Philip Yang <philip.yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>