pwm: mediatek: Implement .get_state() callback

pwm: mediatek: Implement .get_state() callback

The registers can be read out just fine on an MT8365. In the assumption
that this works on all supported devices, a .get_state() callback can be
implemented. This enables consumers to make use of pwm_get_state_hw() and
improves the usefulness of /sys/kernel/debug/pwm.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250725154506.2610172-15-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>