net/iavf: remove extra check in vector Tx

net/iavf: remove extra check in vector Tx

In the vector Tx path, the function iavf_xmit_pkts_vec_xxx compares
nb_pkts and the txq->rs_thresh and passes the minimum of these as an
argument to iavf_xmit_fixed_burst_vec_xxx.
Inside iavf_xmit_fixed_burst_vec_xxx, the same check is performed again.

This patch removes the redundant check from the
iavf_xmit_fixed_burst_vec_xxx function.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>