auxdisplay: 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: Paul Burton <paul.burton@imgtec.com>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Paul Burton <paul.burton@mips.com>
Tested-by: Paul Burton <paul.burton@mips.com> # for img-ascii-lcd