ARM: shmobile: armadillo: initialize all struct pwm_lookup members

Initializing all the struct pwm_lookup members allows to get rid of the
struct tpu_pwm_platform_data as the polarity initialization will be
taken care of by the PWM core.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>