options: allow '*' as value for protocols and families

No functional change, just a little bit of consistency with src / dest
specifiers where '*' means 'any' or 'all'. To follow the principle of
least surprise, allow the some for family and protocol options.

  option proto '*' is equivalent to option proto 'all'
  option family '*' is equivalent to option family 'any'

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>