defconfig: 8994: Enable logging of context switch latencies

In order to gather data regarding context switch latenies on the
arm64 architecture turn on CONFIG_ARCH_WANTS_CTXSW_LOGGING.

Change-Id: I3065c1880f49b68fc7ee0825cfac080e88238008
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>