Convert QMP capabilities to domain capabilities

Convert QMP capabilities to domain capabilities

the QMP capabilities:
  {"return":
    {
      "sgx": true,
      "section-size": 1024,
      "flc": true
    }
  }

the domain capabilities:
  <sgx>
    <flc>yes</flc>
    <epc_size>1</epc_size>
  </sgx>

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Haibin Huang <haibin.huang@intel.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>