tracing/ftrace: factorize the tracing files creation

Impact: cleanup

Most of the tracing files creation follow the same pattern:

ret = debugfs_create_file(...)
if (!ret)
	pr_warning("Couldn't create ... entry\n")

Unify it!

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238109938-11840-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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

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

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

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

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

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

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

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