dpctl: Expand the flow dump type filter

dpctl: Expand the flow dump type filter

Added new types to the flow dump filter, and allowed multiple filter
types to be passed at once, as a comma separated list. The new types
added are:
 * tc - specifies flows handled by the tc dp
 * non-offloaded - specifies flows not offloaded to the HW
 * all - specifies flows of all types

The type list is now fully parsed by the dpctl, and a new struct was
added to dpif which enables dpctl to define which types of dumps to
provide, rather than passing the type string and having dpif parse it.

Signed-off-by: Gavi Teitz <gavi@mellanox.com>
Acked-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>