Revert "defconfig: enable BFQ I/O scheduler as default"

BFQ I/O scheduler causes bootloop on 4.2.2

This reverts commit 4018a9e1ecf50d05db6db8d89f1c36f72c50dc22.

Change-Id: I1810b3fa7aefa92200718318bc22a32f0d4f345e