ARM: AM33xx: Remove the unused voltagedomain data

Now that there is a way to tell the powerdomain core about
missing voltage domain auto-scaling control in SoCs', get rid of the dummy
voltage domain data populated for AM33xx devices.

Acked-by: Nishanth Menon <nm@ti.com>
Acked-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Afzal Mohammed <afzal@ti.com> # am335x evm
Signed-off-by: Kevin Hilman <khilman@linaro.org>