Revert "block: Enable BFQ io scheduler as default"

'commit abc0fc15dcec ("block: Enable BFQ io scheduler as default")'
This is to fix the Native Daemon and Zygote Preload regressions
during bootup.

Change-Id: I4cfb40d0622319ce84d17fa409a4fcb5ab429dbc
Signed-off-by: Pradeep P V K <pragalla@codeaurora.org>