Updated ODP-DPDK README
Updated ODP-DPDK README

- export RTE_SDK and RTE_TARGET before compiling ODP
- new commands for odp_l2fwd and pktio
- cleanup

Signed-off-by: Venkatesh Vivekanandan <4c07d742fff36fe39d99fbe1c45af3bcf3245007@linaro.org>
Reviewed-by: Anders Roxell <b4e8e89057bc64bc4f9625a4a821c9ac177a7ed2@linaro.org>

nmorey/odp,nmorey/odp,ravineet-singh/odp,dkrot/odp,kalray/odp-mppa,kalray/odp-mppa,erachmi/odp,kalray/odp-mppa,erachmi/odp,nmorey/odp,kalray/odp-mppa,mike-holmes-linaro/odp,kalray/odp-mppa,ravineet-singh/odp,kalray/odp-mppa,rsalveti/odp,rsalveti/odp,dkrot/odp,rsalveti/odp,erachmi/odp,rsalveti/odp,ravineet-singh/odp,ravineet-singh/odp,mike-holmes-linaro/odp,kalray/odp-mppa,erachmi/odp,mike-holmes-linaro/odp,dkrot/odp,rsalveti/odp,dkrot/odp,mike-holmes-linaro/odp,nmorey/odp