perf tools: Fix the check for parameterized field in event term

The format_alias() function in util/pmu.c has a check to
detect whether the event has parameterized field ( =? ).
The string alias->terms contains the event and if the event
has user configurable parameter, there will be presence of
sub string "=?" in the alias->terms.

Snippet of code:

 /* Paramemterized events have the parameters shown. */
       if (strstr(alias->terms, "=?")) {
               /* No parameters. */
               snprintf(buf, len, "%.*s/%s/", (int)pmu_name_len, pmu->name, alias->name);

if "strstr" contains the substring, it returns a pointer
and hence enters the above check which is not the expected
check. And hence "perf list" doesn't have the parameterized
fields in the result.

Fix this check to use:

if (!strstr(alias->terms, "=?")) {

With this change, perf list shows the events correctly with
the strings showing parameters.

Before the fix:

 # ./perf list|grep -w PM_PAU_CYC
  hv_24x7/PM_PAU_CYC/                                [Kernel PMU event]

With this fix:

 # ./perf list|grep -w PM_PAU_CYC
  hv_24x7/PM_PAU_CYC,chip=?/                         [Kernel PMU event]

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Shivani Nittor <shivani@linux.ibm.com>
Cc: Tanushree.Shah@ibm.com
Cc: Tejas.Manhas1@ibm.com
Cc: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmu.c

@@ -2134,7 +2134,7 @@ static char *format_alias(char *buf, int len, const struct perf_pmu *pmu,
 						   skip_duplicate_pmus);
 
 	/* Paramemterized events have the parameters shown. */
-	if (strstr(alias->terms, "=?")) {
+	if (!strstr(alias->terms, "=?")) {
 		/* No parameters. */
 		snprintf(buf, len, "%.*s/%s/", (int)pmu_name_len, pmu->name, alias->name);
 		return buf;