defconfig: enable uid stats on sdm660

'commit 6a61b529 ("ANDROID: uid_sys_stats: rename
uid_cputime.c to uid_sys_stats.c")' renamed CONFIG_UID_CPUTIME
to CONFIG_UID_SYS_STATS and enabled the new config on relevant
defconfigs except sdm660. Enable it and sync the config to
remove the reference to CONFIG_UID_CPUTIME. Task IO accounting
is enabled as CONFIG_UID_SYS_STATS depends on it.

Change-Id: Ib7163cf090c4fe86030469a257c49be1f6558984
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>