tty: metag_da: Convert timers to use timer_setup()

tty: metag_da: 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: James Hogan <james.hogan@imgtec.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: James Hogan <jhogan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>