ftrace: Allow for function tracing instance to filter functions

Create a "set_ftrace_filter" and "set_ftrace_notrace" files in the instance
directories to let users filter of functions to trace for the given instance.

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

diff --cc include/linux/ftrace.h
Simple merge

diff --cc kernel/trace/ftrace.c
Simple merge

diff --cc kernel/trace/trace.c
Simple merge

diff --cc kernel/trace/trace.h
Simple merge

diff --cc kernel/trace/trace_functions.c
Simple merge