pwm: mediatek: Drop the check for of_device_get_match_data()

This patch drop the check for of_device_get_match_data. Due to the only
way call driver probe is compatible match. The data pointer which points
to the SoC specify data is directly set by driver, and it should not be
NULL in our case. We can safety remove the check for the result of
of_device_get_match_data().

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Sam Shih <sam.shih@mediatek.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>