tracing/tools: Fix incorrcet short option in usage text for --threads

tracing/tools: Fix incorrcet short option in usage text for --threads

The help message incorrectly listed '-t' as the short option for
--threads, but the actual getopt_long configuration uses '-e'.
This mismatch can confuse users and lead to incorrect command-line
usage. This patch updates the usage string to correctly show:
	"-e, --threads NRTHR"
to match the implementation.

Note: checkpatch.pl reports a false-positive spelling warning on
'Run', which is intentional.

Link: https://patch.msgid.link/20251106031040.1869-1-zhangchujun@cmss.chinamobile.com
Signed-off-by: Zhang Chujun <zhangchujun@cmss.chinamobile.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>