rtla: Fix uninitialized variable found

Variable found is not being initialized, in the case where the desired
mount is not found the variable contains garbage. Fix this by initializing
it to zero.

Link: https://lore.kernel.org/all/20230727150117.627730-1-colin.i.king@gmail.com/

Fixes: a957cbc ("rtla: Add -C cgroup support")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

Author: ColinIanKing

tools/tracing/rtla/src/utils.c

@@ -538,7 +538,7 @@ static const int find_mount(const char *fs, char *mp, int sizeof_mp)
 {
 	char mount_point[MAX_PATH];
 	char type[100];
-	int found;
+	int found = 0;
 	FILE *fp;
 
 	fp = fopen("/proc/mounts", "r");