iio: adc: mt6577_auxadc: Fix kernel panic on suspend

Commit a2d518fb ("iio: adc: mt6577_auxadc: Simplify with device managed function")
simplified the driver with devm hooks, but wrongly states that the
platform_set_drvdata(), platform_get_drvdata() are unused after the
simplification: the driver data is infact used in .suspend() and
.resume() PM callbacks, currently producing a kernel panic.

Reintroduce the call to platform_set_drvdata() in the probe function

Fixes: a2d518fb ("iio: adc: mt6577_auxadc: Simplify with device managed function")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Link: https://lore.kernel.org/r/20231010121940.159696-1-angelogioacchino.delregno@collabora.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/mt6577_auxadc.c

@@ -293,6 +293,7 @@ static int mt6577_auxadc_probe(struct platform_device *pdev)
 	mt6577_auxadc_mod_reg(adc_dev->reg_base + MT6577_AUXADC_MISC,
 			      MT6577_AUXADC_PDN_EN, 0);
 	mdelay(MT6577_AUXADC_POWER_READY_MS);
+	platform_set_drvdata(pdev, indio_dev);
 
 	ret = devm_add_action_or_reset(&pdev->dev, mt6577_power_off, adc_dev);
 	if (ret)