net: hns: Fix ethtool private flags

commit d61d263c8d82db7c4404a29ebc29674b1c0c05c9 upstream.

The driver implementation returns support for private flags, while
no private flags are present. When asked for the number of private
flags it returns the number of statistic flag names.

Fix this by returning EOPNOTSUPP for not implemented ethtool flags.

Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>