pwmround/pwmset: Fix check for invalid duty_offset

.period_length_ns == .duty_offset_ns == 0 is a valid waveform that
shouldn't trigger a warning.

Link: https://lore.kernel.org/r/20250710160417.2089742-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
2 files changed