tc: Add flow control setting on PRIO qdisc

* Enable filter fw, qdiscs prio, and qdisc fifo.
* Add "flow enable|disable" clause for PRIO qdisc
* Now using sanitized kernel headers

CRs-fixed: 555466
Change-Id: I7ccfe9717bf21738c66b33dbafe04b2c3a3a912a
(cherry picked from commit f238dceaa69cd866e1fb068c0c658eb659f5c8ed)
(cherry picked from commit 2c252e1350ba7fde0e27a17c159b561ba0e0945d)