net/bnxt: fix tunnel port accounting

net/bnxt: fix tunnel port accounting

Fix the tunnel port counting logic.
Currently we are incrementing the port count without checking
the if bnxt_hwrm_tunnel_dst_port_alloc would return success or failure.
Modify the logic to increment it only if the firmware returns success.

Fixes: 10d074b2022d ("net/bnxt: support tunneling")
Cc: stable@dpdk.org
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Lance Richardson <lance.richardson@broadcom.com>