plat-omap: omap34xx: fix wrong cpu freq steps

Before this commit, the kernel always reported 4 cpu frequencies
where we would have one dublicate.
I am not completely sure if this is a gcc problem, defy+ specific
or another random bug.
Just fix it.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
omap2: clock: fix gpu overclock

Since the last cpu frequency changes, gpu overclock
was broken;
<4>[   66.902435] GPU Control try to set clock rate to 266 MHz
<4>[   66.902465] omap2_clksel_round_rate_div: force change to S800M
<4>[   66.902465] omap2_clksel_round_rate_div: force change to S800M
<4>[   66.902465] omap2_clksel_set_rate: validrate (250000000) != rate (266666666)

This is due S800M got redefined and the dividers for gpu would
calculate a new max. Fix this by defining a local parent rate
to calculate the new gpu max rate.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>