ring-buffer: Remove useless unused tracing_off_permanent()

The tracing_off_permanent() call is a way to disable all ring_buffers.
Nothing uses it and nothing should use it, as tracing_off() and
friends are better, as they disable the ring buffers related to
tracing. The tracing_off_permanent() even disabled non tracing
ring buffers. This is a bit drastic, and was added to handle NMIs
doing outputs that could corrupt the ring buffer when only tracing
used them. It is now obsolete and adds a little overhead, it should
be removed.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

include/linux/kernel.h

@@ -532,12 +532,6 @@ bool mac_pton(const char *s, u8 *mac);
  *
  * Most likely, you want to use tracing_on/tracing_off.
  */
-#ifdef CONFIG_RING_BUFFER
-/* trace_off_permanent stops recording with no way to bring it back */
-void tracing_off_permanent(void);
-#else
-static inline void tracing_off_permanent(void) { }
-#endif
 
 enum ftrace_dump_mode {
 	DUMP_NONE,