coccinelle: Improve setup_timer.cocci matching

This improves the patch mode of setup_timer.cocci. Several patterns
were missing:
 - assignments-before-init_timer() cases
 - limit the .data case removal to the specific struct timer_list instance
 - handling calls by dereference (timer->field vs timer.field)

Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Michal Marek <mmarek@suse.com>
Cc: cocci@systeme.lip6.fr
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>