OMAP2/3 PM: create the OMAP PM interface and add a default OMAP PM no-op layer

The interface provides device drivers, CPUFreq, and DSPBridge with a
means of controlling OMAP power management parameters that are not yet
supported by the Linux PM PMQoS interface.  Copious documentation is
in the patch in Documentation/arm/OMAP/omap_pm and the interface
header file, arch/arm/plat-omap/include/mach/omap-pm.h.

Thanks to Rajendra Nayak <rnayak@ti.com> for adding CORE (VDD2) OPP
support and moving the OPP table initialization earlier in the event
that the clock code needs them.  Thanks to Tero Kristo
<tero.kristo@nokia.com> for fixing the parameter check in
omap_pm_set_min_bus_tput().  Jouni signed off on Tero's patch.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Tero Kristo <tero.kristo@nokia.com>
Signed-off-by: Jouni Högander <jouni.hogander@nokia.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Igor Stoppa <igor.stoppa@nokia.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Anand Sawant <sawant@ti.com>
Cc: Sakari Poussa <sakari.poussa@nokia.com>
Cc: Veeramanikandan Raju <veera@ti.com>
Cc: Karthik Dasu <karthik-dp@ti.com>