mm: pass readahead info down to the i/o scheduler

Some i/o schedulers (i.e. row-iosched, cfq-iosched) deploy an idling
algorithm in order to be better synced with the readahead algorithm.
Idling is a prediction algorithm for incoming read requests.

In this patch we mark pages which are part of a readahead window, by
setting a newly introduced flag. With this flag, the i/o scheduler can
identify a request which is associated with a readahead page. This
enables the i/o scheduler's idling mechanism to be en-sync with the
readahead mechanism and, in turn, can increase read throughput.

Change-Id: I0654f23315b6d19d71bcc9cc029c6b281a44b196
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>
aries: Enable SG chaining support

from commit dc21904 for herring
Add 1100 OC steps

Change-Id: Id2200023812d3dac79c36b41faa57b61db84a0c1

Conflicts:

	arch/arm/mach-s5pv210/cpufreq.c
	arch/arm/mach-s5pv210/include/mach/cpu-freq-v210.h
	arch/arm/mach-s5pv210/mach-aries.c