defconfig: 8084: enable coresight hardware event driver

The STM hardware event interface allows monitoring and tracing
of hardware events. The CoreSight Hardware Event driver programs
various hardware event mux control registers to configure these
hardware events based on user selection. Enable this functionality
for 8084.

Change-Id: I66c1aa7d572a9816152f12c0993e95a5ee86c446
Signed-off-by: Pushkar Joshi <pushkarj@codeaurora.org>