libtracefs: Fix tracefs_instance_set_buffer_size() for individual CPUs

The tracefs_instance_set_buffer_size() function, when passed an update for
an individual CPU, writes in "val" and not val (the string that holds the
value to set). This is obviously wrong. Fix it.

Link: https://lore.kernel.org/linux-trace-devel/20230103183846.5ffdef36@gandalf.local.home

Fixes: 48c026fbb430e ("libtracefs: Add tracefs_instance_set_buffer_size() API")
Reported-by: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
diff --git a/src/tracefs-instance.c b/src/tracefs-instance.c
index 6905f61..57f5c7f 100644
--- a/src/tracefs-instance.c
+++ b/src/tracefs-instance.c
@@ -419,7 +419,7 @@
 			return ret;
 		}
 
-		ret = tracefs_instance_file_write(instance, path, "val");
+		ret = tracefs_instance_file_write(instance, path, val);
 		free(path);
 	}
 	free(val);