OMAPDSS: DSS: Scale DSS OPP according to pixel clock rate

Before enabling pixel clock DSS should set its OPP
for OPP framework to set correct VDD_CORE voltage level.

When pixel clock is disabled DSS can set the lowest OPP.

Change-Id: Ia1459614ae306dba9b048b149e474442e2880bba
Signed-off-by: Taras Kondratiuk <taras@ti.com>

Conflicts:
	drivers/video/omap2/dss/dsi.c
OMAP4460: TWL/TPS data: update retention voltages to spec rev 0.3

Update retention voltages from Operating Conditions Data Manual
Addendum Revision 0.3 (August 2011).

OFF voltage is also updated as per requirement of 4460 OFF mode
conditions.

Change-Id: I558f0a483911b2616d0a19f9272a03258e35904a
Signed-off-by: Nishanth Menon <nm@ti.com>

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