OMAP4: PM: OPP/Clock: Add virtual clocks for high IVA OPPs support

To get correct frequencies for IVA OPP higher than OPP100
IVA DPLL should be reconfigured.
Tesla is also supplied from the same IVA DPLL, so frequency on DSP
should be reconfigured together with IVAHD frequency.

This is achieved by adding virtual clocks for IVA and DSP.
Main logic is implemented in IVA virtual clock which sets
frequency for both IVAHD and DSP.
DSP virtual clock is just a dummy clock and it do nothing.

Necessary DSP OPP is set via IVA virtual clock by using DVFS framework feature:
if device on which OPP is set is not the primary device in voltage domain,
then constraint to the same OPP is set for primary device.
In case of DSP the primary device is IVAHD.

If switching to the lower OPP will cause IVA DPLL scaling up,
then frequency of IVA and DSP should be scaled down before DPLL.

Change-Id: I1b229f1d52f0f8bfa4f65f08221df1e1ba6194bc
[jagadeeshwar.reddy@ti.com: original patch author for 4430]
Signed-off-by: Jagadeeshwar Reddy <jagadeeshwar.reddy@ti.com>
[taras@ti.com: modified and extended for all OMAP44xx]
Signed-off-by: Taras Kondratiuk <taras@ti.com>

Conflicts:
	arch/arm/mach-omap2/opp4xxx_data.c