selftest: intel_pstate: debug support message from aperf.c and return value

Additional message along with an error message which is more
verbose for debug support from aperf.c and updated with the
new return value "KSFT_SKIP".
Signed-off-by: NJeffrin Jose T [Rajagiri SET] <ahiliation@gmail.com>
Signed-off-by: NShuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/intel_pstate/aperf.c

@@ -9,6 +9,8 @@
 #include <sys/timeb.h>
 #include <sched.h>
 #include <errno.h>
+#include <string.h>
+#include "../kselftest.h"
 
 void usage(char *name) {
 	printf ("Usage: %s cpunum\n", name);
@@ -41,8 +43,8 @@ int main(int argc, char **argv) {
 	fd = open(msr_file_name, O_RDONLY);
 
 	if (fd == -1) {
-		perror("Failed to open");
-		return 1;
+		printf("/dev/cpu/%d/msr: %s\n", cpu, strerror(errno));
+		return KSFT_SKIP;
 	}
 
 	CPU_ZERO(&cpuset);