This patch adds VMDq loopback pf support for i350 devices. The patch
is necessary since the register that enabled loopback was moved and
renamed from DTXSWC to TXSWC.
Signed-off-by: "Akeem G. Abodunrin" <akeem.g.abodunrin@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>