ethtool: add ETHTOOL_COALESCE_ALL_PARAMS define

This bitmask represents all existing coalesce parameters.

Signed-off-by: Antonio Cardace <acardace@redhat.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>