ftrace: Make ftrace_modify_all_code() global for archs to use

Rename __ftrace_modify_code() to ftrace_modify_all_code() and make
it global for all archs to use. This will remove the duplication
of code, as archs that can modify code without stop_machine()
can use it directly outside of the stop_machine() call.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 609948e..cd72ace 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -319,6 +319,8 @@
 extern void ftrace_call(void);
 extern void mcount_call(void);
 
+void ftrace_modify_all_code(int command);
+
 #ifndef FTRACE_ADDR
 #define FTRACE_ADDR ((unsigned long)ftrace_caller)
 #endif