netdev-linux: Support for SFQ, FQ_CoDel and CoDel qdiscs.

netdev-linux: Support for SFQ, FQ_CoDel and CoDel qdiscs.

This patch adds support for SFQ, CoDel and FQ_CoDel classless qdiscs to Open vSwitch. It also removes the requirement for a QoS to have at least one Queue (as this makes no sense when using classless qdiscs). I have also not implemented class_{get,set,delete,get_stats,dump_stats} because they are meant for qdiscs with classes.

Signed-off-by: Jonathan Vestin <jonavest@kau.se>
[blp@nicira.com mostly applied stylistic changes]
Signed-off-by: Ben Pfaff <blp@nicira.com>