iio: trigger: stm32-timer-trigger: make use of regmap_clear_bits(), regmap_set_bits()

Instead of using regmap_update_bits() and passing the mask twice, use
regmap_set_bits().

Instead of using regmap_update_bits() and passing val = 0, use
regmap_clear_bits().

Suggested-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://patch.msgid.link/20240617-review-v3-41-88d1338c4cca@baylibre.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>