Implements workqueue latency function.

Test cases:

  # perf kwork -k workqueue lat

    Kwork Name                     | Cpu  | Avg delay     | Count     | Max delay     | Max delay start     | Max delay end       |
   --------------------------------------------------------------------------------------------------------------------------------
    (w)vmstat_update               | 0001 |      5.004 ms |         1 |      5.004 ms |      44001.745646 s |      44001.750650 s |
    (w)vmstat_update               | 0006 |      1.773 ms |         1 |      1.773 ms |      44000.830840 s |      44000.832613 s |
    (w)vmstat_shepherd             | 0000 |      0.992 ms |         8 |      2.474 ms |      44007.717845 s |      44007.720318 s |
    (w)vmstat_update               | 0000 |      0.974 ms |         5 |      2.624 ms |      44004.785970 s |      44004.788594 s |
    (w)e1000_watchdog              | 0002 |      0.687 ms |         5 |      2.632 ms |      44005.009334 s |      44005.011966 s |
    (w)vmstat_update               | 0002 |      0.307 ms |         1 |      0.307 ms |      44004.817395 s |      44004.817702 s |
    (w)vmstat_update               | 0004 |      0.296 ms |         1 |      0.296 ms |      43997.913677 s |      43997.913973 s |
    (w)mix_interrupt_randomness    | 0000 |      0.283 ms |       285 |      3.724 ms |      44006.790889 s |      44006.794613 s |
    (w)neigh_managed_work          | 0001 |      0.271 ms |         1 |      0.271 ms |      43997.665542 s |      43997.665813 s |
    (w)vmstat_update               | 0005 |      0.261 ms |         1 |      0.261 ms |      44007.820542 s |      44007.820803 s |
    (w)neigh_managed_work          | 0004 |      0.220 ms |         1 |      0.220 ms |      44002.953287 s |      44002.953507 s |
    (w)neigh_periodic_work         | 0004 |      0.217 ms |         1 |      0.217 ms |      43999.929718 s |      43999.929935 s |
    (w)mix_interrupt_randomness    | 0002 |      0.199 ms |         5 |      0.310 ms |      44005.012316 s |      44005.012625 s |
    (w)vmstat_update               | 0003 |      0.199 ms |         4 |      0.307 ms |      44005.714391 s |      44005.714699 s |
    (w)gc_worker                   | 0001 |      0.071 ms |       173 |      1.128 ms |      44002.062579 s |      44002.063707 s |
   --------------------------------------------------------------------------------------------------------------------------------
    INFO: 0.020% skipped events (17 including 10 raise, 7 entry, 0 exit)
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220709015033.38326-13-yangjihong1@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>