kernel: sched: prevent task_group() being called a lot in set_task_rq()

Performance improvement -> more, when autogroup is enabled
drivers: i2c: i2c-omap: use usleep range instead of msleep

msleep(1) means to wait up 20ms. i2c doesn't take that much time. Should result in better performance
cpuidle: governors: menu: decrease nr_iowait_cpu for idle
mm: added ZBUD backport from 3.11