OMAP3: PM: Adding smartreflex driver support.

OMAP3: PM: Adding smartreflex driver support.

SmartReflex modules do adaptive voltage control for real-time
voltage adjustments. With Smartreflex the power supply voltage
can be adapted to the silicon performance(manufacturing process,
temperature induced performance, age induced performance etc).

There are differnet classes of smartreflex implementation.
	Class-0: Manufacturing Test Calibration
	Class-1: Boot-Time Software Calibration
	Class-2: Continuous Software Calibration
	Class-3: Continuous Hardware Calibration
	Class-4: Fully Integrated Power Management

OMAP3 has two smartreflex modules one associated with VDD MPU and the
other associated with VDD CORE.
This patch adds support for  smartreflex driver. The driver is designed
for Class-1 , Class-2 and Class-3 support and is  a platform driver.
Smartreflex driver can be enabled through a Kconfig option
"SmartReflex support" under "System type"->"TI OMAP implementations" menu.

Smartreflex autocompensation feature can be enabled runtime through
a debug fs option.
To enable smartreflex autocompensation feature
	echo 1 > /debug/voltage/vdd_<X>/smartreflex/autocomp
To disable smartreflex autocompensation feature
	echo 0 > /debug/voltage/vdd_<X>/smartreflex/autocomp

where X can be mpu, core , iva etc.

This patch contains code originally in linux omap pm branch.
Major contributors to this driver are
Lesly A M, Rajendra Nayak, Kalle Jokiniemi, Paul Walmsley,
Nishant Menon, Kevin Hilman.

Signed-off-by: Thara Gopinath <thara@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>