i40e: Enable 'channel' mode in mqprio for TC configs

The i40e driver is modified to enable the new mqprio hardware
offload mode and factor the TCs and queue configuration by
creating channel VSIs. In this mode, the priority to traffic
class mapping and the user specified queue ranges are used
to configure the traffic classes by setting the mode option to
'channel'.

Example:
  map 0 0 0 0 1 2 2 3 queues 2@0 2@2 1@4 1@5\
  hw 1 mode channel

qdisc mqprio 8038: root  tc 4 map 0 0 0 0 1 2 2 3 0 0 0 0 0 0 0 0
             queues:(0:1) (2:3) (4:4) (5:5)
             mode:channel
             shaper:dcb

The HW channels created are removed and all the queue configuration
is set to default when the qdisc is detached from the root of the
device.

This patch also disables setting up channels via ethtool (ethtool -L)
when the TCs are configured using mqprio scheduler.

The patch also limits setting ethtool Rx flow hash indirection
(ethtool -X eth0 equal N) to max queues configured via mqprio.
The Rx flow hash indirection input through ethtool should be
validated so that it is within in the queue range configured via
tc/mqprio. The bound checking is achieved by reporting the current
rss size to the kernel when queues are configured via mqprio.

Example:
  map 0 0 0 1 0 2 3 0 queues 2@0 4@2 8@6 11@14\
  hw 1 mode channel

Cannot set RX flow hash configuration: Invalid argument

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>