Revert "block: Add URGENT request notification support to CFQ scheduler"

This reverts commit b410a82118cdaa1dc92759e7995c20dcce0d1f1a.
The reverted commit was identified as the cause of the FS error
mentioned in the CR bellow.
It's reverted till further annalists of the root cause of FS error.

Change-Id: Ia75216de8012a2491b87f33e8c21f75592d87c80
CRs-fixed: 531257
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>