ixgbe: incorrect XDP ring accounting in ethtool tx_frame param

Changing the TX ring parameters with an XDP program attached may
cause the XDP queues to be cleared and the TX rings to be incorrectly
configured.

Fix by doing correct ring accounting in setup call.

Fixes: 33fdc82f ("ixgbe: add support for XDP_TX action")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>