parisc/ftrace: Fix function graph tracing disablement

Due to an apparent copy-paste bug, the parisc implementation of
ftrace_disable_ftrace_graph_caller() doesn't actually do anything.
It enables the (already-enabled) static key rather than disabling it.

The result is that after function graph tracing has been "disabled", any
subsequent (non-graph) function tracing will inadvertently also enable
the slow fgraph return address hijacking.

Fixes: 98f2926 ("parisc/ftrace: use static key to enable/disable function graph tracer")
Cc: stable@vger.kernel.org # 5.16+
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>

Author: jpoimboe

arch/parisc/kernel/ftrace.c

@@ -87,7 +87,7 @@ int ftrace_enable_ftrace_graph_caller(void)
 
 int ftrace_disable_ftrace_graph_caller(void)
 {
-	static_key_enable(&ftrace_graph_enable.key);
+	static_key_disable(&ftrace_graph_enable.key);
 	return 0;
 }
 #endif