linux-phytec-fsl

net/mlx4_en: break out tx_desc write into separate function

In preparation for writing the tx descriptor from multiple functions,
create a helper for both normal and blueflame access.

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>