cpufreq: Break out early when frequency equals target_freq

Many drivers keep frequencies in frequency table in ascending
or descending order. When governor tries to change to policy->min
or policy->max respectively then the cpufreq_frequency_table_target
could return on first iteration. This will save some iteration cycles.

So, break out early when a frequency in cpufreq_frequency_table
equals to target one.

Testing this during kernel compilation using ondemand governor
with a frequency table in ascending order, the
cpufreq_frequency_table_target returned early on the first
iteration at about 30% of times called.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Lens-F <tnoah12@gmail.com>
CHROMIUM: allow clocksources to be selected earlier during boot

Global and per-CPU timers ought to be initialized once SMP initialization
is complete.  Although the clocksources associated with these timers may
not be registered until later in the boot process, they should be ready
to go once registered.  We'd like to stop using the super low-resolution
boot clocksource (jiffies) as soon as possible since devices may rely on
accurate timekeeping while being brought up during boot, so move
clocksource_done_booting() to arch_initcall time so that we can switch
to a higher-resolution clocksrouce earlier in the boot process.

TEST=Pit and Lumpy both still boot reliably.  Boot time on Pit improves
considerably:
Before: [    3.032967] VFS: Mounted root ...
After:  [    1.855936] VFS: Mounted root ...
Lumpy boot time improves very slightly:
Before: [    1.786347] VFS: Mounted root ...
After:  [    1.754297] VFS: Mounted root ...

Signed-off-by: Lens-F <tnoah12@gmail.com>
kswapd: Introduce congestion_wait_kswapd

congestion_wait for kswapd is similar to congestion_wait, the vital
difference is that congestion_wait_kswapd uses schedule_timeout
instead of io_schedule_timeout (which can cause IO wait conditions,
due to nr_iowait usage).

Derived from: https://github.com/oppo-source/Find5-Kernel-Source-4.2/commit/c7b44a43a970b699ecd68655bd6f83a8fbb3d74d
Original author: huanggd @oppo-source

Signed-off-by: Luis Cruz <ljc2491@gmail.com>
Signed-off-by: Lens-F <tnoah12@gmail.com>