ARM: OMAP AM33xx: voltagedomain: Add voltage domain data

Currently dummy voltage domain data is being created
in order to succeed boot process, nothing has been done
w.r.t actual hardware (voltage control).

Also, hook up the AM33XX voltage domain to OMAP framework.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Afzal Mohammed <afzal@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
[paul@pwsan.com: updated for 3.5]
Signed-off-by: Paul Walmsley <paul@pwsan.com>