iio: adc: stm32-dfsdm: Use pm_runtime_resume_and_get() to replace open coding.

Found using coccicheck script under review at:
https://lore.kernel.org/lkml/20210427141946.2478411-1-Julia.Lawall@inria.fr/

This is a prequel to taking a closer look at the runtime pm in IIO drivers
in general.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/20210509113354.660190-16-jic23@kernel.org

drivers/iio/adc/stm32-dfsdm-core.c

@@ -135,11 +135,9 @@ int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
 	int ret;
 
 	if (atomic_inc_return(&priv->n_active_ch) == 1) {
-		ret = pm_runtime_get_sync(dev);
-		if (ret < 0) {
-			pm_runtime_put_noidle(dev);
+		ret = pm_runtime_resume_and_get(dev);
+		if (ret < 0)
 			goto error_ret;
-		}
 
 		/* select clock source, e.g. 0 for "dfsdm" or 1 for "audio" */
 		clk_src = priv->aclk ? 1 : 0;