misc: fs_loader: Add function to get the chosen loader

The fs_loader device is used to pull in settings via the chosen node.
However, there was no library function for this, so arria10 was doing it
explicitly. This function subsumes that, and uses ofnode_get_chosen_node
instead of navigating the device tree directly. Because fs_loader pulls
its config from the environment by default, it's fine to create a device
with nothing backing it at all. Doing this allows enabling
CONFIG_FS_LOADER without needing to modify the device tree.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/fpga/socfpga_arria10.c b/drivers/fpga/socfpga_arria10.c
index 3b785e6..96b1950 100644
--- a/drivers/fpga/socfpga_arria10.c
+++ b/drivers/fpga/socfpga_arria10.c
@@ -777,42 +777,20 @@
 {
 	struct fpga_loadfs_info fpga_loadfs;
 	struct udevice *dev;
-	int status, ret, size;
+	int status, ret;
 	u32 buffer = (uintptr_t)buf;
 	size_t buffer_sizebytes = bsize;
 	size_t buffer_sizebytes_ori = bsize;
 	size_t total_sizeof_image = 0;
 	ofnode node;
-	const fdt32_t *phandle_p;
-	u32 phandle;
 
 	node = get_fpga_mgr_ofnode(ofnode_null());
-
-	if (ofnode_valid(node)) {
-		phandle_p = ofnode_get_property(node, "firmware-loader", &size);
-		if (!phandle_p) {
-			node = ofnode_path("/chosen");
-			if (!ofnode_valid(node)) {
-				debug("FPGA: /chosen node was not found.\n");
-				return -ENOENT;
-			}
-
-			phandle_p = ofnode_get_property(node, "firmware-loader",
-						       &size);
-			if (!phandle_p) {
-				debug("FPGA: firmware-loader property was not");
-				debug(" found.\n");
-				return -ENOENT;
-			}
-		}
-	} else {
+	if (!ofnode_valid(node)) {
 		debug("FPGA: FPGA manager node was not found.\n");
 		return -ENOENT;
 	}
 
-	phandle = fdt32_to_cpu(*phandle_p);
-	ret = uclass_get_device_by_phandle_id(UCLASS_FS_FIRMWARE_LOADER,
-					     phandle, &dev);
+	ret = get_fs_loader(&dev);
 	if (ret)
 		return ret;