add extra free kbytes tunable

Add a userspace visible knob to tell the VM to keep an extra amount
of memory free, by increasing the gap between each zone's min and
low watermarks.

This is useful for realtime applications that call system
calls and have a bound on the number of allocations that happen
in any short time period.  In this application, extra_free_kbytes
would be left at an amount equal to or larger than than the
maximum number of allocations that happen in any burst.

It may also be useful to reduce the memory use of virtual
machines (temporarily?), in a way that does not cause memory
fragmentation like ballooning does.

[ccross]
Revived for use on old kernels where no other solution exists.
The tunable will be removed on kernels that do better at avoiding
direct reclaim.

Change-Id: I765a42be8e964bfd3e2886d1ca85a29d60c3bb3e
Signed-off-by: Rik van Riel<riel@redhat.com>
Signed-off-by: Colin Cross <ccross@android.com>
board-latona: don't initialize all the serial ports available

Revert also ecad852 ("mach: serial: fix issues with bluetooth wake on latona")
OMAPDSS: DSS2: add early suspend support
mach: pm: simplify minimum dsp frequency sysfs control
mach: pm: allow to change OPP voltage if SR is disabled

Requires 6695dbb ("SmartReflex: allow to selectively disable SR calibrations")

volt_calibrated is used instead of volt_nominal if it's nonzero.
latona defconfigs: enable keychord driver

This is required to trigger services through keycodes.
latona defconfigs: don't optimize for size