Allow for rate limiting Tx queues. Bitrate is set in
Mbps(megabits per second).

Mbps max-rate is set for the queue via sysfs:
/sys/class/net/<iface>/queues/tx-<queue>/tx_maxrate
ex: echo 100 >/sys/class/net/ens7/queues/tx-0/tx_maxrate
    echo 200 >/sys/class/net/ens7/queues/tx-1/tx_maxrate
Note: A value of zero for tx_maxrate means disabled,
default is disabled.
Signed-off-by: Usha Ketineni <usha.k.ketineni@intel.com>
Co-developed-by: Tarun Singh <tarun.k.singh@intel.com>
Signed-off-by: Tarun Singh <tarun.k.singh@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>