ARM: OMAP: SmartReflex: Move smartreflex driver to drivers/

After a clean-up of the interfaces the OMAP Smartreflex IP driver is now a
generic driver. Move it to drivers/power/avs/.

The build is controlled by the following Kconfig options:
 . CONFIG_POWER_AVS: general knob for Adaptive Voltage Scaling support,
 . CONFIG_POWER_AVS_OMAP: AVS(Adaptive Voltage Scaling)
   support on OMAP containing the version 1 or version 2 of the SmartReflex IP,
 . CONFIG_POWER_AVS_OMAP_CLASS3: Class 3 implementation of Smartreflex.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Signed-off-by: J Keerthy <j-keerthy@ti.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>