clk: renesas: r9a06g032: Fix memory leak in error path

[ Upstream commit f8def051bbcf8677f64701e9699bf6d11e2780cd ]

The current code uses of_iomap() to map registers but never calls
iounmap() on any error path after the mapping. This causes a memory
leak when probe fails after successful ioremap, for example when
of_clk_add_provider() or r9a06g032_add_clk_domain() fails.

Replace of_iomap() with devm_of_iomap() to automatically unmap the
region on probe failure. Update the error check accordingly to use
IS_ERR() and PTR_ERR() since devm_of_iomap() returns ERR_PTR on error.

Fixes: 4c3d885 ("clk: renesas: Renesas R9A06G032 clock driver")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20251030061603.1954-1-vulab@iscas.ac.cn
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[uli: backport to 4.19]
Signed-off-by: Ulrich Hecht <uli@kernel.org>
Reviewed-by: Pavel Machek <pavel@nabladev.com>

Author: ISCAS-Vulab

drivers/clk/renesas/r9a06g032-clocks.c

@@ -830,9 +830,10 @@ static int __init r9a06g032_clocks_probe(struct platform_device *pdev)
 	if (IS_ERR(mclk))
 		return PTR_ERR(mclk);
 
-	clocks->reg = of_iomap(np, 0);
-	if (WARN_ON(!clocks->reg))
-		return -ENOMEM;
+	clocks->reg = devm_of_iomap(dev, np, 0, NULL);
+	if (IS_ERR(clocks->reg))
+		return PTR_ERR(clocks->reg);
+
 	for (i = 0; i < ARRAY_SIZE(r9a06g032_clocks); ++i) {
 		const struct r9a06g032_clkdesc *d = &r9a06g032_clocks[i];
 		const char *parent_name = d->source ?