ethtool: netlink: Add missing ethnl_ops_begin/complete

Accessing an ethernet device that is powered off or clock gated might
cause the CPU to hang. Add ethnl_ops_begin/complete in
ethnl_set_features() to protect against this.

Fixes: 0980bfcd ("ethtool: set netdev features with FEATURES_SET request")
Signed-off-by: Ludvig Pärsson <ludvig.parsson@axis.com>
Link: https://lore.kernel.org/r/20240117-etht2-v2-1-1a96b6e8c650@axis.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>