net/bnxt: fix reporting of link status

net/bnxt: fix reporting of link status

This patch fixes incorrect reporting of link status

1) When link is down, set speed to zero. Otherwise a wrong non-zero
   speed will be displayed.

2) DAC cables can detect there is a signal, but it necessarily does not
   mean link is up. Code previously treated this as link up.

Fixes: 7bc8e9a227cc ("net/bnxt: support async link notification")
Cc: stable@dpdk.org
Signed-off-by: Stephen Hurd <stephen.hurd@broadcom.com>
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>