boardconfig: use racer_f2fs kernel
hammerhead: Reconfigure sync freq feature

Now that interactive is working properly, there is no
need for overly aggressive cpu freqs. Also, remove
the unused config for target loads.

Change-Id: I36e2fecfc24f0dd7da8224638a902d2c3be83b47
hammerhead: Optimize I/O scheduling

Inspired by bacon. We aren't suffering from slowdowns
during bootanim, anyway this is the right way to do it.

Change-Id: Icf3d9d6e52926012a4b7fdfdc1456a37ad782e71