iio: adc: ad7192: Simplify using devm_clk_get_optional_enabled()

If st->mclk is not NULL, then st->clock_sel is either AD7192_CLK_EXT_MCLK2
or AD7192_CLK_EXT_MCLK1_2.

So devm_clk_get_optional_enabled() can be used instead of hand writing it.
This saves some line of code.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/7dbe973905f1fdae5d2f5ae5a3b01dd1d6a9925b.1686774340.git.christophe.jaillet@wanadoo.frSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -972,11 +972,6 @@ static void ad7192_reg_disable(void *reg)
 	regulator_disable(reg);
 }
 
-static void ad7192_clk_disable(void *clk)
-{
-	clk_disable_unprepare(clk);
-}
-
 static int ad7192_probe(struct spi_device *spi)
 {
 	struct ad7192_state *st;
@@ -1044,7 +1039,7 @@ static int ad7192_probe(struct spi_device *spi)
 
 	st->fclk = AD7192_INT_FREQ_MHZ;
 
-	st->mclk = devm_clk_get_optional(&spi->dev, "mclk");
+	st->mclk = devm_clk_get_optional_enabled(&spi->dev, "mclk");
 	if (IS_ERR(st->mclk))
 		return PTR_ERR(st->mclk);
 
@@ -1052,15 +1047,6 @@ static int ad7192_probe(struct spi_device *spi)
 
 	if (st->clock_sel == AD7192_CLK_EXT_MCLK1_2 ||
 	    st->clock_sel == AD7192_CLK_EXT_MCLK2) {
-		ret = clk_prepare_enable(st->mclk);
-		if (ret < 0)
-			return ret;
-
-		ret = devm_add_action_or_reset(&spi->dev, ad7192_clk_disable,
-					       st->mclk);
-		if (ret)
-			return ret;
-
 		st->fclk = clk_get_rate(st->mclk);
 		if (!ad7192_valid_external_frequency(st->fclk)) {
 			dev_err(&spi->dev,