time_zone_manager: Stop on comma

This is a deviation from the reference time zone implementation. The
actual code will set a pointer to the time zone name here, but for us we
have a limited number of characters to work with, and the name of the
time zone here could be larger than 8 characters.

We can make the assumption that time zone names greater than five
characters in length include a comma that denotes more data. Nintendo
just truncates that data for the name, so we can do the same.

time_zone_manager: Check for length of array

Just to be double sure that we never break past the array length,
directly compare against it.