pinctrl: canaan: k230: Fix NULL pointer dereference when parsing devicetree

When probing the k230 pinctrl driver, the kernel triggers a NULL pointer
dereference. The crash trace showed:
[    0.732084] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000068
[    0.740737] ...
[    0.776296] epc : k230_pinctrl_probe+0x1be/0x4fc

In k230_pinctrl_parse_functions(), we attempt to retrieve the device
pointer via info->pctl_dev->dev, but info->pctl_dev is only initialized
after k230_pinctrl_parse_dt() completes.

At the time of DT parsing, info->pctl_dev is still NULL, leading to
the invalid dereference of info->pctl_dev->dev.

Use the already available device pointer from platform_device
instead of accessing through uninitialized pctl_dev.

Fixes: d94a32a ("pinctrl: canaan: k230: Fix order of DT parse and pinctrl register")
Signed-off-by: Jiayu Du <jiayu.riscv@isrc.iscas.ac.cn>
Signed-off-by: Linus Walleij <linusw@kernel.org>

Author: duge1975

drivers/pinctrl/pinctrl-k230.c

@@ -65,6 +65,7 @@ struct k230_pmx_func {
 };
 
 struct k230_pinctrl {
+	struct device		*dev;
 	struct pinctrl_desc	pctl;
 	struct pinctrl_dev	*pctl_dev;
 	struct regmap		*regmap_base;
@@ -470,7 +471,7 @@ static int k230_pinctrl_parse_groups(struct device_node *np,
 				     struct k230_pinctrl *info,
 				     unsigned int index)
 {
-	struct device *dev = info->pctl_dev->dev;
+	struct device *dev = info->dev;
 	const __be32 *list;
 	int size, i, ret;
 
@@ -511,7 +512,7 @@ static int k230_pinctrl_parse_functions(struct device_node *np,
 					struct k230_pinctrl *info,
 					unsigned int index)
 {
-	struct device *dev = info->pctl_dev->dev;
+	struct device *dev = info->dev;
 	struct k230_pmx_func *func;
 	struct k230_pin_group *grp;
 	static unsigned int idx, i;
@@ -596,6 +597,8 @@ static int k230_pinctrl_probe(struct platform_device *pdev)
 	if (!info)
 		return -ENOMEM;
 
+	info->dev = dev;
+
 	pctl = &info->pctl;
 
 	pctl->name	= "k230-pinctrl";