ovsdb: Require column type "min" value be 0 or 1.

ovsdb: Require column type "min" value be 0 or 1.

A "min" value greater than 1 is problematic for the database.  There is no
reasonable way to synthesize a default value for such a column: keys in a
set or map must unique, so the database cannot, say, simply set a set of
3 or more integers to [0, 0, 0].

This should have no effect on the vswitch in practice because it does not
have any columns that require more than one element.