net/bnxt: fix Rx descriptor status

net/bnxt: fix Rx descriptor status

Fix a number of issues in the bnxt receive descriptor status
function, including:
   - Provide status of receive descriptor instead of completion
     descriptor.
   - Remove invalid comparison of raw ring index with masked ring
     index.
   - Correct misinterpretation of offset parameter as ring index.
   - Correct misuse of completion ring index for mbuf ring (the
     two rings have different sizes).

Fixes: 0fe613bb87b2 ("net/bnxt: support Rx descriptor status")
Cc: stable@dpdk.org
Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Reviewed-by: Andy Gospodarek <gospo@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>