gpiolib: Fix of_node inconsistency

Some platforms are not setting of_node in the driver. On these platforms
defining gpio-reserved-ranges on device tree leads to kernel crash.

It is due to some parts of the gpio core relying on the driver to set up
of_node,while other parts do themselves.This inconsistent behaviour leads
to a crash.

gpiochip_add_data_with_key() calls gpiochip_init_valid_mask() with of_node
as NULL. of_gpiochip_add() fills "of_node" and calls
of_gpiochip_init_valid_mask().

The fix is to move the assignment to chip->of_node from of_gpiochip_add()
to gpiochip_add_data_with_key().

Signed-off-by: Biju Das <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Tested-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpiolib-of.c

···
 {
 	int status;
 
-	if ((!chip->of_node) && (chip->parent))
-		chip->of_node = chip->parent->of_node;
-
 	if (!chip->of_node)
 		return 0;
 

drivers/gpio/gpiolib.c

···
 	/* If the gpiochip has an assigned OF node this takes precedence */
 	if (chip->of_node)
 		gdev->dev.of_node = chip->of_node;
+	else
+		chip->of_node = gdev->dev.of_node;
 #endif
 
 	gdev->id = ida_simple_get(&gpio_ida, 0, 0, GFP_KERNEL);