bus: bt1-axi: Optimize the return points in the driver

It's better to have a single return statement where it's applicable
instead of returning from a conditional statement if-clause. Let's
do this in the request registers, clock and IRQ methods.

Link: https://lore.kernel.org/r/20200528145050.5203-5-Sergey.Semin@baikalelectronics.ruSigned-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: soc@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/bus/bt1-axi.c

@@ -124,12 +124,10 @@ static int bt1_axi_request_regs(struct bt1_axi *axi)
 	}
 
 	axi->qos_regs = devm_platform_ioremap_resource_byname(pdev, "qos");
-	if (IS_ERR(axi->qos_regs)) {
+	if (IS_ERR(axi->qos_regs))
 		dev_err(dev, "Couldn't map AXI-bus QoS registers\n");
-		return PTR_ERR(axi->qos_regs);
-	}
 
-	return 0;
+	return PTR_ERR_OR_ZERO(axi->qos_regs);
 }
 
 static int bt1_axi_request_rst(struct bt1_axi *axi)
@@ -173,12 +171,10 @@ static int bt1_axi_request_clk(struct bt1_axi *axi)
 	}
 
 	ret = devm_add_action_or_reset(axi->dev, bt1_axi_disable_clk, axi);
-	if (ret) {
+	if (ret)
 		dev_err(axi->dev, "Can't add AXI clock disable action\n");
-		return ret;
-	}
 
-	return 0;
+	return ret;
 }
 
 static int bt1_axi_request_irq(struct bt1_axi *axi)
@@ -192,12 +188,10 @@ static int bt1_axi_request_irq(struct bt1_axi *axi)
 
 	ret = devm_request_irq(axi->dev, axi->irq, bt1_axi_isr, IRQF_SHARED,
 			       "bt1-axi", axi);
-	if (ret) {
+	if (ret)
 		dev_err(axi->dev, "Couldn't request AXI EHB IRQ\n");
-		return ret;
-	}
 
-	return 0;
+	return ret;
 }
 
 static ssize_t count_show(struct device *dev,