kernel/trace/trace.h: Remove duplicate header of trace_seq.h

Remove duplicate header which is included twice.

Link: http://lkml.kernel.org/r/1553725186-41442-1-git-send-email-jagdsh.linux@gmail.com

Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Jagadeesh Pagadala <jagdsh.linux@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>