mm: memory: reduce fault_around_bytes

mapping multiple pages on a fault result in page_check_references
hitting more number of referenced inactive pages and this results
in increased pressure on reclaim. Reduce it to the lowest possible
value. Reduced kswapd wakeups are observed with this change.

Change-Id: I03c6cac9f28fa328abab7b40f5f01144084a147c
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>