regulator: fixed: Prevent NULL pointer dereference when !CONFIG_OF

Use of_device_get_match_data which has NULL test for match before
dereference match->data. Add NULL test for drvtype so it still works
for fixed_voltage_ops when !CONFIG_OF.

Signed-off-by: Axel Lin <[e-mail]>
Reviewed-by: Philippe Schenker <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/fixed.c

···
 	struct device *dev = &pdev->dev;
 	struct fixed_voltage_config *config;
 	struct fixed_voltage_data *drvdata;
-	const struct fixed_dev_type *drvtype =
-		of_match_device(dev->driver->of_match_table, dev)->data;
+	const struct fixed_dev_type *drvtype = of_device_get_match_data(dev);
 	struct regulator_config cfg = { };
 	enum gpiod_flags gflags;
 	int ret;
···
 	drvdata->desc.type = REGULATOR_VOLTAGE;
 	drvdata->desc.owner = THIS_MODULE;
 
-	if (drvtype->has_enable_clock) {
+	if (drvtype && drvtype->has_enable_clock) {
 		drvdata->desc.ops = &fixed_voltage_clkenabled_ops;
 
 		drvdata->enable_clock = devm_clk_get(dev, NULL);