regulator: stm32-pwr: fix of_iomap leak

Smatch reports:
drivers/regulator/stm32-pwr.c:166 stm32_pwr_regulator_probe() warn:
'base' from of_iomap() not released on lines: 151,166.

In stm32_pwr_regulator_probe(), base is not released
when devm_kzalloc() fails to allocate memory or
devm_regulator_register() fails to register a new regulator device,
which may cause a leak.

To fix this issue, replace of_iomap() with
devm_platform_ioremap_resource(). devm_platform_ioremap_resource()
is a specialized function for platform devices.
It allows 'base' to be automatically released whether the probe
function succeeds or fails.

Besides, use IS_ERR(base) instead of !base
as the return value of devm_platform_ioremap_resource()
can either be a pointer to the remapped memory or
an ERR_PTR() encoded error code if the operation fails.

Fixes: dc62f951 ("regulator: stm32-pwr: Fix return value check in stm32_pwr_regulator_probe()")
Signed-off-by: YAN SHI <m202071378@hust.edu.cn>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202304111750.o2643eJN-lkp@intel.com/Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Link: https://lore.kernel.org/r/20230412033529.18890-1-m202071378@hust.edu.cnSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/stm32-pwr.c

@@ -129,17 +129,16 @@ static const struct regulator_desc stm32_pwr_desc[] = {
 
 static int stm32_pwr_regulator_probe(struct platform_device *pdev)
 {
-	struct device_node *np = pdev->dev.of_node;
 	struct stm32_pwr_reg *priv;
 	void __iomem *base;
 	struct regulator_dev *rdev;
 	struct regulator_config config = { };
 	int i, ret = 0;
 
-	base = of_iomap(np, 0);
-	if (!base) {
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base)) {
 		dev_err(&pdev->dev, "Unable to map IO memory\n");
-		return -ENOMEM;
+		return PTR_ERR(base);
 	}
 
 	config.dev = &pdev->dev;