defconfig: enable task io stats

CTS test is failing because of zero values in /proc/uid_io/stats
so enabling task io accounting config to fill this node with
proper details.

Change-Id: Iae2c2d650efc638c0c3ff39a6576f75ba1e2615e
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>