Revert "misc: uid_stat: Include linux/atomic.h instead of asm/atomic.h"

This reverts commit 8d3a6c15.

This series of patches revert AOSP UID_STAT and NET_ACTIVITY_STATS drivers.
I could not find any meaningful usage of these interfaces in AOSP master.

UID_STAT driver expose "/proc/uid_stat/*" interfaces but it is only
used in AOSP master as in what appears be an out of date bandwidth
test in frameworks/base and in somewhat recent battery utils test
in external/chromium-trace project.

NET_ACTIVITY_STATS driver expose "/proc/net/stat/activity" interface
but I can not track its usage anywhere in AOSP at all.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>