ARM: pxa: hx4700: use PWM_LOOKUP to initialize struct pwm_lookup

Use the new variant of the PWM_LOOKUP macro to initialize the PWM lookup
table.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>