The maximum frequency for applications was set to 430 MHz before,
while some Dingoos can handle higher frequencies. Now the limit is set to
the theoretical maximum frequency of 500 MHz.
For the menu itself the maximum frequency is set to a safer 408 MHz,
to avoid over-eager users from putting their system in an unusable state
that is difficult to recover from.
Also the frequency settings are now done in 24 MHz increments, to match
the limitations of the current JZ4740 kernel. Note that only new entries
are rounded to 24 MHz multiples, existing entries stay as they are.
