ixgbe: allow IPsec Tx offload in VEPA mode

When it's possible that the PF might end up trying to send a
packet to one of its own VFs, we have to forbid IPsec offload
because the device drops the packets into a black hole.
See commit 47b6f500 ("ixgbe: disallow IPsec Tx offload
when in SR-IOV mode") for more info.

This really is only necessary when the device is in the default
VEB mode.  If instead the device is running in VEPA mode,
the packets will go through the encryption engine and out the
MAC/PHY as normal, and get "hairpinned" as needed by the switch.

So let's not block IPsec offload when in VEPA mode.  To get
there with the ixgbe device, use the handy 'bridge' command:
	bridge link set dev eth1 hwmode vepa

Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>