dpdk: Update version to 21.02
dpdk: Update version to 21.02

Update of DPDK to latest stable release.
As this introduces new build dependency, it also adds install
of pyelftools to the build step. (note however that flush of pip downloads
cache dir is required)
https://doc.dpdk.org/guides-21.02/rel_notes/release_21_02.html

Type: improvement
Signed-off-by: Kepka, Krzysztof <385319df26b46b2bbaad96b56475519ea45330c8@intel.com>
Change-Id: I7ed2ca965f01c1062f5abc25ea428e8c1a016366

chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp