soc: renesas: rcar-sysc: Mark device node OF_POPULATED after init

The R-Car System Controller (SYSC) driver registers PM domains from an
early_initcall().  It does not use a platform driver, as secondary CPU
startup on R-Car H1 needs to control the CPU power domains, before
initialization of the driver framework.

As fw_devlink only considers devices, it does not know that the System
Controller is ready.  Hence probing of on-chip devices that are part of
the SYSC PM domain fails if fw_devlink is enabled:

    probe deferral - supplier e6180000.system-controller not ready

Fix this by setting the OF_POPULATED flag for the SYSC device node after
successful initialization.  This will make of_link_to_phandle() ignore
the SYSC device node as a dependency, and consumer devices will be
probed again.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210128082847.2205950-1-geert+renesas@glider.be

drivers/soc/renesas/rcar-sysc.c

@@ -434,6 +434,8 @@ static int __init rcar_sysc_pd_init(void)
 	}
 
 	error = of_genpd_add_provider_onecell(np, &domains->onecell_data);
+	if (!error)
+		of_node_set_flag(np, OF_POPULATED);
 
 out_put:
 	of_node_put(np);