eal: provide API for querying valid socket ids

eal: provide API for querying valid socket ids

During lcore scan, find all socket ID's and store them, and
provide public API to query valid socket id's. This will break
the ABI, so bump ABI version.

Also, remove deprecation notice corresponding to this change.

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Gowrishankar Muthukrishnan <gowrishankar.m@linux.vnet.ibm.com>