ARM: dts: msm: add perf-events support for apq8084

Add the device definitions for the performance monitor
unit on apq8084. This enables the perf-events
subsystem.

Change-Id: I95fa6810b59248fc478c28d739de0e800e2cdb5e
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>