ARM: dts: msm: Add power management devices for MSM8992

Add DT entries for SPM devices for CCI/L2/CPU levels. Also add
lpm-levels node to support hierarchical cluster low power modes.

Change-Id: I2668025894572f029838f104dfe2a61c2d5289b3
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>