perf docs: Fix a typo in 'perf probe' man page: l20th -> 120th

Fix a minor typo in 'perf probe' doc.

Fixes: 631c9def804b2c92 ("perf probe: Support --line option to show probable source-code lines")
Signed-off-by: qinyu <[e-mail]>
Acked-by: Ian Rogers <[e-mail]>
Cc: Feilong Lin <[e-mail]>
Cc: Hewenliang <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf-probe.txt

···
 and 'ALN2' is end line number in the file. It is also possible to specify how
 many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
 for searching a specific function when several functions share same name.
-So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function.
+So, "source.c:100-120" shows lines between 100th to 120th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function.
 
 LAZY MATCHING
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