f2fs: add lock elapsed time trace facility for f2fs rwsemphore

f2fs: add lock elapsed time trace facility for f2fs rwsemphore

This patch adds lock elapsed time trace facility for f2fs rwsemphore.

If total elapsed time of critical region covered by lock exceeds a
threshold, it will print tracepoint to dump information of lock related
context, including:
- thread information
- CPU/IO priority
- lock information
- elapsed time
 - total time
 - running time (depend on CONFIG_64BIT)
 - runnable time (depend on CONFIG_SCHED_INFO and CONFIG_SCHEDSTATS)
 - io sleep time (depend on CONFIG_TASK_DELAY_ACCT and
		  /proc/sys/kernel/task_delayacct)
 - other time    (by default other time will account nonio sleep time,
                  but, if above kconfig is not defined, other time will
                  include runnable time and/or io sleep time as wll)

output:
    f2fs_lock_elapsed_time: dev = (254,52), comm: sh, pid: 13855, prio: 120, ioprio_class: 2, ioprio_data: 4, lock_name: cp_rwsem, lock_type: rlock, total: 1000, running: 993, runnable: 2, io_sleep: 0, other: 5

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>