msm: limits: Move profile switch interface to sysfs

At present, LMH interface supports for the LMH hardware to
switch profiles and this can be achieved by using the debug
file system interface.

Move this interface from debug file system to system
file system, so that it can be accessed in devices without
the debug file system mounted.

Below are the new sysfs interfaces,
/sys/class/msm_limits/lmh-profile/level
	 - Set or get the current LMH operating profile.
/sys/class/msm_limits/lmh-profile/total_levels
	- Total operating profile levels supported in this device.
/sys/class/msm_limits/lmh-profile/available_levels
	- Lists the available profile levels for this device.

Change-Id: Id2920c69bb2033c2026e9dd7f8d50ed4347887ff
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>