memory: renesas-rpc-if: simplify with PTR_ERR_OR_ZERO

Use PTR_ERR_OR_ZERO to make the code a little bit simpler.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200724074038.5597-17-krzk@kernel.org

drivers/memory/renesas-rpc-if.c

@@ -199,10 +199,8 @@ int rpcif_sw_init(struct rpcif *rpc, struct device *dev)
 		rpc->dirmap = NULL;
 
 	rpc->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
-	if (IS_ERR(rpc->rstc))
-		return PTR_ERR(rpc->rstc);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(rpc->rstc);
 }
 EXPORT_SYMBOL(rpcif_sw_init);