api: pktio: specify that pool type must be ODP_POOL_PACKET
api: pktio: specify that pool type must be ODP_POOL_PACKET

The pool passed to odp_pktio_open() must be of type ODP_POOL_PACKET so
add a note to clarify.

Signed-off-by: Stuart Haslam <1fce01f364ef5298e64e07a42e08efeef153fa98@linaro.org>
Reviewed-by: Petri Savolainen <d528fd253b9aaf78fa72edbcc6249e82047f6ce6@nokia.com>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

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