eal: remove dead code on NUMA node detection

eal: remove dead code on NUMA node detection

RTE_EAL_ALLOW_INV_SOCKET_ID had been introduced and documented as used
with xen dom0 support (dropped for some time now).

Closely looking at this, the code was changed later and ensures that the
socket id is in the [0..RTE_MAX_NUMA_NODES] range anyway.

Let's drop this dead code and the build option with it.

Fixes: 94ef2964148a ("eal/linux: fix numa node detection")
Cc: stable@dpdk.org
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>