iio: trigger: stm32-timer: remove unnecessary update event

There is no need to explicitly generate update event to update
timer master mode.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/trigger/stm32-timer-trigger.c

@@ -297,9 +297,6 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev,
 			     strlen(master_mode_table[i]))) {
 			regmap_update_bits(priv->regmap, TIM_CR2, mask,
 					   i << shift);
-			/* Make sure that registers are updated */
-			regmap_update_bits(priv->regmap, TIM_EGR,
-					   TIM_EGR_UG, TIM_EGR_UG);
 			return len;
 		}
 	}