dm: gpio: Add live tree support

Add support for requesting GPIOs with a live device tree.

This involves adjusting the function signature for the legacy function
gpio_request_by_name_nodev(), so fix up all callers.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes to stm32f746-disco.c:
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/st/stm32f746-disco/stm32f746-disco.c b/board/st/stm32f746-disco/stm32f746-disco.c
index aeaa311..7a6d93c 100644
--- a/board/st/stm32f746-disco/stm32f746-disco.c
+++ b/board/st/stm32f746-disco/stm32f746-disco.c
@@ -101,7 +101,7 @@
 	if (node < 0)
 		return -1;
 
-	gpio_request_by_name_nodev(gd->fdt_blob, node, "led-gpio", 0, &gpio,
+	gpio_request_by_name_nodev(offset_to_ofnode(node), "led-gpio", 0, &gpio,
 				   GPIOD_IS_OUT);
 
 	if (dm_gpio_is_valid(&gpio)) {
@@ -115,8 +115,8 @@
 	if (node < 0)
 		return -1;
 
-	gpio_request_by_name_nodev(gd->fdt_blob, node, "button-gpio", 0, &gpio,
-				   GPIOD_IS_IN);
+	gpio_request_by_name_nodev(offset_to_ofnode(node), "button-gpio", 0,
+				   &gpio, GPIOD_IS_IN);
 
 	if (dm_gpio_is_valid(&gpio)) {
 		if (dm_gpio_get_value(&gpio))