pwm: Drop unused forward declaration from pwm.h
The declaration was necessary until commit cc2d22477779 ("pwm: Drop
per-chip dbg_show callback").
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
authored by