eal: limit telemetry to primary processes

eal: limit telemetry to primary processes

Telemetry interface should be exposed for primary processes only, since
secondary processes will conflict on socket creation, and since all
data in secondary process is generally available to primary. For
example, all device stats for ethdevs, cryptodevs, etc. will all be
common across processes.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Ciara Power <ciara.power@intel.com>
Tested-by: Conor Walsh <conor.walsh@intel.com>