net/bnxt: fix xstats get

net/bnxt: fix xstats get

Fix to return count in xstats get op in all cases.
Driver was returning 0 if the 'xstats' parameter being passed to
xstats_get_op was NULL. This won't work on some applications that
rely on a valid count being passed even in this case so that it can
allocate memory accordingly followed by a reissue of the xstats_get_op
to get the actual stats populated by the driver.

Fixes: 063e59ddd28e ("net/bnxt: fix crash in xstats get")
Cc: stable@dpdk.org
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Lance Richardson <lance.richardson@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>