net: sched: return -ENOENT when trying to remove filter from non-existent chain

When chain 0 was implicitly created, removal of non-existent filter from
chain 0 gave -ENOENT. Once chain 0 became non-implicit, the same call is
giving -EINVAL. Fix this by returning -ENOENT in that case.

Reported-by: Roman Mashak <mrv@mojatatu.com>
Fixes: f71e0ca4 ("net: sched: Avoid implicit chain 0 creation")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>