msm: lpm-stats: Support cpu and cluster lpm stats

On current architectures the number of hardware levels that support low
power modes is limited to cpus and l2. These cpus and l2 in-turn support
a fixed set of low power modes.
Newer architectures can have a hierarchy of clusters. Different clusters
in this hierarchy can support different low power modes.
CPU's, in different clusters, may support different low power modes.
The low power modes supported by each of these levels is defined in the
device tree for each target.
Add new apis to receive information about each level's low power modes and
to collect and print stats for each the levels low power modes as listed
in the device tree.

cluster 0
|	|_ _ lpm 0
|	|_ _ lpm 1
|	|
|	*
|
|_ _ _ _cluster 0
|	|	|_ _ lpm 0
|	|	|_ _ lpm 1
|	|	|
|	|	*
|	|_ _ _ _ _ _cpu 0
|	|		|_ _ lpm 0
|	|		|_ _ lpm 1
|	|		|
|	|		*
|	|
|	|_ _ _ _ _ _cpu 1
|	|		|_ _ lpm 0
|	|		|_ _ lpm 1
|	|		|
|	|		*
|	*
|
|_ _ _ _cluster 1
|	|	|_ _ lpm 0
|	|	|_ _ lpm 1
|	|	|
*	|	*
	|_ _ _ _ _ _cpu 100
	|		|_ _ lpm 0
	|		|_ _ lpm 1
	|		|
	|		*
	|
	|_ _ _ _ _ _cpu 101
	|		|_ _ lpm 0
	|		|_ _ lpm 1
	|		|
	|		*
	*

Change-Id: If1e8a099f95ff541557f37eeae3332eaf67ac748
Signed-off-by: Karthik Parsha <kparsha@codeaurora.org>