clk: rockchip: don't return NULL when registering mmc branch fails

Avoid return NULL if rockchip_clk_register_mmc fails, otherwise
rockchip_clk_register_branches print "unknown clock type". The acutal
case is that it's a known clock type but we fail to regiser it, which
may makes user confuse the reason of failure.
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

drivers/clk/rockchip/clk-mmc-phase.c

@@ -150,7 +150,7 @@ struct clk *rockchip_clk_register_mmc(const char *name,
 
 	mmc_clock = kmalloc(sizeof(*mmc_clock), GFP_KERNEL);
 	if (!mmc_clock)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	init.name = name;
 	init.num_parents = num_parents;
@@ -172,11 +172,7 @@ struct clk *rockchip_clk_register_mmc(const char *name,
 
 	clk = clk_register(NULL, &mmc_clock->hw);
 	if (IS_ERR(clk))
-		goto err_free;
+		kfree(mmc_clock);
 
 	return clk;
-
-err_free:
-	kfree(mmc_clock);
-	return NULL;
 }