Refresh rate of the LCD.

As the LCD is not memory mapped, the driver has to make the work by
software. This means you should be careful setting this value higher.
If your CPUs are really slow or you feel the system is slowed down,
decrease the value.

Be careful modifying this value to a very high value:
You can freeze the computer, or the LCD maybe can't draw as fast as you
are requesting.

If you don't know what I'm talking about, ignore it.

If you compile this as a module, you can still override this
value using the module parameters.