ARM: dts: msm: add avtimer info for 8994

avtimer is used for synchronization of audio and video
during the playback/capture usecase. This change adds
avtimer register addresses in device tree for 8994 target.

Change-Id: I76ceab4ffd7039f44282a7996a22c50b6fd8b57b
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>
Signed-off-by: Kuirong Wang <kuirongw@codeaurora.org>
Signed-off-by: Fred Oh <fred@codeaurora.org>