net/bnxt: fix resource cleanup

net/bnxt: fix resource cleanup

Fix resource cleanup in port close.
Once the pointers are freed, set them to NULL.
Make sure access to the pointers is validated before use.

Fixes: bb81e07323bb ("net/bnxt: support LED on/off")
Fixes: 804e746c7b73 ("net/bnxt: add hardware resource manager init code")
Fixes: 1d0704f4d793 ("net/bnxt: add device configure operation")
Fixes: 698aa7e95325 ("net/bnxt: add code to determine the Tx COS queue")
Fixes: 322bd6e70272 ("net/bnxt: add port representor infrastructure")
Fixes: 0bf5a0b5ebb8 ("net/bnxt: add a failure log")
Cc: stable@dpdk.org
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>