ANDROID: Skip building uid_sys_stats and keyreset drivers as modules

Few Android drivers viz. uid_sys_stats and keyreset/combo fail to
build as kernel modules.

uid_sys_stats.ko failed for undefined "tasklist_lock", which got
un-exported in commit c59923a1 ("remove the tasklist_lock export").
Quoting from the commit, "Modules have  no business looking at it,
and all instances in drivers have been due to use of too-lowlevel
APIs. Having this symbol exported prevents moving to more scalable
locking schemes for the task list.". So instead of exporting
tasklist_lock again, lets not build uid_sys_stats driver as module.
Similarly skip building keyreset driver as module which call
sys_sync() syscall.

To keep things in perspective we don't build these drivers as modules
in later kernels (android-4.4/4.9) as well.

Change-Id: I6371df72d79c7ad0f0c08e6ebf7e16f1b0970761
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>