bnxt_en: Fix .ndo_setup_tc() to include XDP rings.

When the number of TX rings is changed in bnxt_setup_tc(), we need to
include the XDP rings in the total TX ring count.

Fixes: 38413406 ("bnxt_en: Add support for XDP_TX action.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>