ARM: dts: msm: add avtimer info for msm8992

avtimer is used for synchronization of audio and video
during the playback/capture usecase. This change adds
avtimer register addresses in device tree for 8992 target

Change-Id: Ia2d2a5c87acabe26671fd26cc20806d64adacc9e
Signed-off-by: Fred Oh <fred@codeaurora.org>