OF: Add a warning in case chosen node is not present

On architectures that only get their bootargs through devicetree's
chosen node (such as RISC-V), that node is mandatory. After a
discussion with Rob [1] I'm adding a warning in case chosen node
is not present, to let users know about it.

[1]: https://patchwork.ozlabs.org/patch/984224/#2016136Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/fdt.c

@@ -1207,8 +1207,12 @@ bool __init early_init_dt_verify(void *params)
 
 void __init early_init_dt_scan_nodes(void)
 {
+	int rc = 0;
+
 	/* Retrieve various information from the /chosen node */
-	of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+	if (!rc)
+		pr_warn("No chosen node found, continuing without\n");
 
 	/* Initialize {size,address}-cells info */
 	of_scan_flat_dt(early_init_dt_scan_root, NULL);