drivers/net: sis: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Cc: Francois Romieu <romieu@fr.zoreil.com>
Cc: Daniele Venzano <venza@brownhat.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Daniele Venzano <venza@brownhat.org>
Signed-off-by: David S. Miller <davem@davemloft.net>