[ticket/11803] Revert POLL_MAX_OPTIONS min value to 0

When it was made the min number of options allowed to a user was 1 but 0 can also be used as it means unlimited.

PHPBB3-11803
Merge remote-tracking branch 'remotes/brunoais/ticket/11803' into develop

* remotes/brunoais/ticket/11803:
  [ticket/11803] Revert POLL_MAX_OPTIONS min value to 0