mbuf: remove physical address alias

mbuf: remove physical address alias

Remove the deprecated buf_physaddr union field from rte_mbuf.
It is replaced with buf_iova which is at the same offset.

The single field buf_physaddr in rte_kni_mbuf is also renamed.

This concludes a 3-year process of semantic change.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
Acked-by: Ray Kinsella <mdr@ashroe.eu>