Restore rw_reg and hw_direct_stats

Restore rw_reg and hw_direct_stats

Note that DPDK 21.11 and above must be built with 'enable_driver_sdk'
option enabled, in order to expose the rte_eth_devices array, now marked
as internal. See
http://doc.dpdk.org/guides-21.11/rel_notes/release_21_11.html#abi-changes
for details. This is done by supplying the '-Denable_driver_sdk=true'
command line parameter, either to 'meson setup', or later on to 'meson
configure', before running 'ninja' and 'ninja install'.

Signed-off-by: Patrice Buriez <patrice.buriez@chenapan.org>
Change-Id: I20db8971818a29ec495b6d8d79cf46f2204631a5