parisc/ftrace: add missing CONFIG_DYNAMIC_FTRACE check

Fixes a bug revealed by -Wmissing-prototypes when
CONFIG_FUNCTION_GRAPH_TRACER is enabled but not CONFIG_DYNAMIC_FTRACE:

 arch/parisc/kernel/ftrace.c:82:5: error: no previous prototype for 'ftrace_enable_ftrace_graph_caller' [-Werror=missing-prototypes]
    82 | int ftrace_enable_ftrace_graph_caller(void)
       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 arch/parisc/kernel/ftrace.c:88:5: error: no previous prototype for 'ftrace_disable_ftrace_graph_caller' [-Werror=missing-prototypes]
    88 | int ftrace_disable_ftrace_graph_caller(void)
       |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/kernel/ftrace.c

@@ -78,7 +78,7 @@ asmlinkage void notrace __hot ftrace_function_trampoline(unsigned long parent,
 #endif
 }
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_FUNCTION_GRAPH_TRACER)
 int ftrace_enable_ftrace_graph_caller(void)
 {
 	static_key_enable(&ftrace_graph_enable.key);