perf tests task_analyzer: Fix bad substitution ${$1}

${$1} gives bad substitution error on sh, bash, and zsh. This seems like
a typo, and this patch modifies it to $1, since that is what it's usage
looks like from wherever `check_exec_0` is called.

This issue due to ${$1} caused all function calls to give error in
`find_str_or_fail` line, and so no test runs completely. But
'perf test "perf script task-analyzer tests"' wrongly reports
that tests passed with the status OK, which is wrong considering
the tests didn't even run completely

Fixes: e8478b84 ("perf test: add new task-analyzer tests")
Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Petar Gligoric <petar.gligoric@rohde-schwarz.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230613164145.50488-16-atrajeev@linux.vnet.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/test_task_analyzer.sh

@@ -31,7 +31,7 @@ report() {
 
 check_exec_0() {
 	if [ $? != 0 ]; then
-		report 1 "invokation of ${$1} command failed"
+		report 1 "invocation of $1 command failed"
 	fi
 }