Set ethtool_ops->supported_coalesce_params to let
the core reject unsupported coalescing parameters.

This driver already correctly rejected almost all
unsupported parameters (missing sample_rate_interval).

As a side effect of these changes the error code for
unsupported params changes from EINVAL to EOPNOTSUPP.
Signed-off-by: NJakub Kicinski <kuba@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>