ARM: dts: msm: add ARM PMU support for trinket

Add dt node to support ARM PMU. This allows the
perf clients to record event related to L1 cache,
cpu clock cycle etc.

Change-Id: I138a3b848475b81ccff7f33338c27ca328795f0d
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>