tracing/function-graph-tracer: Use the %pf format

Remove the obsolete seq_print_ip_sym() usage and replace it
by the %pf format in order to print function symbols.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1247107590-6428-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>