pinctrl: fix pinmux_hog_maps when ctrl_dev_name is not set

The ctrl_dev_name is optional for struct pinmux_map assuming
that ctrl_dev is set. Without this patch we can get:

Unable to handle kernel NULL pointer dereference at virtual
address 00000000
...
(pinmux_hog_maps+0xa4/0x20c)
(pinctrl_register+0x2a4/0x378)
...

Fix this by adding adding a test for map->ctrl_dev.
Additionally move the test for map->ctrl_dev earlier
to optimize out the loop a bit.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinmux.c

@@ -978,9 +978,12 @@ int pinmux_hog_maps(struct pinctrl_dev *pctldev)
 	for (i = 0; i < pinmux_maps_num; i++) {
 		struct pinmux_map const *map = &pinmux_maps[i];
 
-		if (((map->ctrl_dev == dev) ||
-		     !strcmp(map->ctrl_dev_name, devname)) &&
-		    map->hog_on_boot) {
+		if (!map->hog_on_boot)
+			continue;
+
+		if ((map->ctrl_dev == dev) ||
+			(map->ctrl_dev_name &&
+				!strcmp(map->ctrl_dev_name, devname))) {
 			/* OK time to hog! */
 			ret = pinmux_hog_map(pctldev, map);
 			if (ret)