Revert "mm: memory: reduce fault_around_bytes"

This reverts commit 23f8a2f5f2e0.

fault_around_bytes were reduced as it was found to cause reclaim
issues. The reclaim issues were mainly because of faultaround
producing young ptes. The following patches will make faultaround
produce old ptes. Thus revert the fault_around_bytes to its
original value.

Change-Id: If9a385eead5a5d7a0d40fed41ddf4753e15d2998
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>