selftests/ftrace: Avoid unlink error on first run

On the first run, ftracetest tries to unlink a symlink that does not
exist.
Use rm -f to avoid the "No such file or directory" error.

Link: https://lore.kernel.org/r/20261014114839.6258-1-jaewon8868@gmail.com
Fixes: 7dc1e125f0 ("ftrace/selftests: Add softlink to latest log directory")
Signed-off-by: Jaewon Jung <jaewon8868@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/ftrace/ftracetest

@@ -243,7 +243,7 @@ else
   mkdir -p $LOG_DIR || errexit "Failed to make a log directory: $LOG_DIR"
   date > $LOG_FILE
   if [ "x-$LINK_PTR" != "x-" ]; then
-    unlink $LINK_PTR
+    rm -f $LINK_PTR
     ln -fs $LOG_DATE $LINK_PTR
   fi
 fi