Updated site class restrictions for ASCE7-16 "D (default)"

Apply the same restriction as is used for "D (determined)" when computing "D (default)".

https://github.com/usgs/earthquake-design-ws/blob/master/src/lib/site-amplification-factory.js#L44:L48

This only applies to the s1 (fv) factor. Leave Ss and "E" site class restrictions unchanged.