tracing: Remove second iterator initializer

The trace iterator is already initialized by trace_init_global_iter(),
so there is no need to initialize it again.

Link: http://lkml.kernel.org/r/CACV3sb+G1YnO6168JhY3dEadmJi58pA5-2cSZT8E0WVHJNFt9Q@mail.gmail.com

Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>