linux-generic: netmap: add netmap_close_descriptors() function
linux-generic: netmap: add netmap_close_descriptors() function

Added a separate function for closing netmap descriptors,
which can be reopened using netmap_start() call.

Signed-off-by: Matias Elo <62402263e8617147f0e4dd5b7f6f8ec67f2b3d2c@nokia.com>
Reviewed-by: Zoltan Kiss <045352d2c5c4a454a2aefff6fa815639b332fd1d@linaro.org>
Reviewed-and-tested-by: Bill Fischofer <52f3c909d51cc5d355a68a403df6906b3c1a8f83@linaro.org>
Signed-off-by: Maxim Uvarov <db4d16e02ae2d7493db430203537da8b2e34f290@linaro.org>

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