Sync with caf's board-8064-gpu.c

Note that this changes the second GPU frequency from 325000000
to 320000000.  This is important because the Fmax table has entries
for 400000000 and 320000000 and the frequencies are matched against
the Fmax table.

Prior to this commit the actual frequencies were 400000000 for the
first two scaling levels and 325000000 was never possible.
Set the default GPU speed to be 200000000

For some reason this seems to let it scale better.  When left at
32000000, it doesn't seem to want to go lower than that for me.

While this doesn't look believable in the code, setting the lower
default speed should in theory have no negative impact as the scaling
will change it as needed.

This also matches the setting of the M7 kernel.
Merge pull request #21 from crpalmer/gpu-misc

GPU cleanup