The current error handling for failed resource setup for xdp_ring
data is a break out of the loop and returning 0 indicated everything
was OK, when in fact it is not.  Fix this by exiting via the
error exit label err_setup_tx that will clean up the resources
correctly and return and error status.

Detected by CoverityScan, CID#1466879 ("Logically dead code")

Fixes: 21092e9c ("ixgbevf: Add support for XDP_TX action")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>