kgsl: add a new governor algorithm. (Thank franciscofranco)
Ditch the older Simple Governor to make place for Interactive. This name
is chosen just to differentiate from the others, but it doesn't behave
like the CPU governor Interactive. This uses a completely different
algorithm to decide when to increase or decrease the GPU frequency. Also
the functions tz_wake and tz_sleep don't do anything, they were a bit
useless at this point after some testing.