MFC r258879:
cxgbe(4):  T4_SET_SCHED_CLASS and T4_SET_SCHED_QUEUE ioctls to program
scheduling classes in the chip and to bind tx queue(s) to a scheduling
class respectively.  These can be used for various kinds of tx traffic
throttling (to force selected tx queues to drain at a fixed Kbps rate,
or a % of the port's total bandwidth, or at a fixed pps rate, etc.).
MFC r259103 and r259382.

r259103:
cxgbe(4): save a copy of the RSS map for each port for the driver's use.

r259382:
Read card capabilities after firmware initialization, instead of setting
them up as part of firmware initialization (which the driver gets to do
only if it's the master driver).

Read the range of tids available for the ETHOFLD functionality if it's
enabled.

New is_ftid() and is_etid() functions to test whether a tid falls within
the range of filter tids or ETHOFLD tids respectively.