This patch resolves an issue where the logic used to detect changes in rx-usecs
was incorrect and was masked by the call to ixgbe_update_rsc().

Setting rx-usecs between 0,2-9 and 1,10 and up requires a reset to allow
ixgbe_configure_tx_ring() to set the correct value for TXDCTL.WTHRESH in
order to avoid Tx hangs with BQL enabled.
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>