gpio: Convert to use APIs which support live DT

Use ofnode_ or dev_ APIs instead of fdt_ and fdtdec_ APIs so that the
driver can support live DT.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 0c01413..4785b6b 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -1100,9 +1100,8 @@
 {
 	int ret;
 
-	ret = fdtdec_parse_phandle_with_args(gd->fdt_blob, dev_of_offset(dev),
-					     list_name, "#gpio-cells", 0, -1,
-					     NULL);
+	ret = dev_read_phandle_with_args(dev, list_name, "#gpio-cells", 0, -1,
+					 NULL);
 	if (ret) {
 		debug("%s: Node '%s', property '%s', GPIO count failed: %d\n",
 		      __func__, dev->name, list_name, ret);