ARM: dts: AM33XX: Add device tree OPP table

Add DT OPP table for AM33XX family of devices. This data is
decoded by OF with of_init_opp_table() helper function.

Also adds cpu0 supply name to the corresponding dts files.
cpu0-supply name is used by cpufreq-cpu0 driver to get the
regulator pointer for voltage modifications.

Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Benoit Cousson <b-cousson@ti.com>