ARM: dts: msm: add PMU support for sdmshrike

Add a device node to enable the armv8 PMU counters. This allows
perf subsystem to measure the hardware/raw performance events, such
as cycles count, instructions count, L1 misses and so on.

Change-Id: I2dae18a539c7dc98252239e92cbd87add55f0a79
Signed-off-by: Vivek Kumar <vivekuma@codeaurora.org>