irqchip/imgpdc: Use resource_size function on resource object

drivers/irqchip/irq-imgpdc.c:327:20-23: WARNING: Suspicious code.
		resource_size is maybe missing with res_regs

Generated by: scripts/coccinelle/api/resource_size.cocci

Signed-off-by: Vasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: marc.zyngier@arm.com
Cc: jason@lakedaemon.net
Link: https://lkml.kernel.org/r/1511215361-8279-1-git-send-email-gomonovych@gmail.com

drivers/irqchip/irq-imgpdc.c

@@ -325,7 +325,7 @@ static int pdc_intc_probe(struct platform_device *pdev)
 
 	/* Ioremap the registers */
 	priv->pdc_base = devm_ioremap(&pdev->dev, res_regs->start,
-				      res_regs->end - res_regs->start);
+				      resource_size(res_regs));
 	if (!priv->pdc_base)
 		return -EIO;