i40e: Resume Port Tx after DCB event

When there are DCB configuration changes based on DCBX the firmware suspends
the port's Tx and generates an event to the PF. The PF is then responsible
to reconfigure the PF VSIs and switching topology as per the updated DCB
configuration and then resume the port's Tx by calling the "Resume Port Tx"
AQ command.

This patch adds this call to the flow that handles DCB re-configuration in
the PF.

Change-ID: I5b860ad48abfbf379b003143c4d3453e2ed5cc1c
Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Tested-By: Jack Morgan <jack.morgan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>