lpm: hide internal data

lpm: hide internal data

Fields except tbl24 and tbl8 in rte_lpm structure have no
need to be exposed to the user.
Hide the unneeded exposure of structure fields for better
ABI maintainability.

Suggested-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Kevin Traynor <ktraynor@redhat.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>