Revert "defconfig: Enable PERF_EVENTS and FUNCTION_TRACER for MSM9615"

This reverts commit c578f420.

Open Embedded uses a newer gcc version which causes this patch
to throw out a forbidden warning. Revert this patch for now, till
the fix can be merged.

Change-Id: I170166028ef2fe7667dfeb522be7000b8bae24cd
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>