clk: renesas: cpg-mssr: propagate return value of_genpd_add_provider_simple()

of_genpd_add_provider_simple() might fail, this patch makes sure we check
the return value of of_genpd_add_provider_simple() by propagating the
return value to the caller of cpg_mssr_add_clk_domain().
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20211117115101.28281-5-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/clk/renesas/renesas-cpg-mssr.c

@@ -590,8 +590,7 @@ static int __init cpg_mssr_add_clk_domain(struct device *dev,
 
 	cpg_mssr_clk_domain = pd;
 
-	of_genpd_add_provider_simple(np, genpd);
-	return 0;
+	return of_genpd_add_provider_simple(np, genpd);
 }
 
 #ifdef CONFIG_RESET_CONTROLLER