perf sched: Fixup header alignment in 'latency' output

Before:

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  Task                  |   Runtime ms  | Switches | Average delay ms | Maximum delay ms | Maximum delay at     |
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  ...                   |               |          |                  |                  |
  git:24540             |    336.622 ms |       10 | avg:    0.032 ms | max:    0.062 ms | max at: 115610.111046 s
  git:24541             |      0.457 ms |        1 | avg:    0.000 ms | max:    0.000 ms | max at:  0.000000 s
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  TOTAL:                |    396.542 ms |      353 |
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After:

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