OMAP3: PM: Adding debug support to Voltage and Smartreflex drivers

This patch adds debug support to the voltage and smartreflex drivers.
This means a whole bunch of voltage processor and smartreflex
parameters are now visible through the pm debugfs.
The voltage parameters can be viewed at
        /debug/voltage/vdd_<x>/<parameter>
and the smartreflex parameters can be viewed at
        /debug/voltage/vdd_<x>/smartreflex/<parameter>

Also smartreflex n-target values are now exposed out at
	/debug/voltage/vdd_<x>/smartreflex/nvalue/<voltage>

This is a read-write interface which means user has the
flexibility to change the n-target values for any opp.

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