net/bnxt: fix flow query count

net/bnxt: fix flow query count

Fix infinite loop in flow query count.
`nxt_resource_idx` could be zero in some cases which is invalid and
should be part of the while loop condition. Also synchronize access to
the flow db using the fdb_lock

Fixes: 306c2d28e247 ("net/bnxt: support count action in flow query")

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Venkat Duvvuru <venkatkumar.duvvuru@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>