ARM: 9120/1: Revert "amba: make use of -1 IRQs warn"

After commit 77a7300a ("of/irq: Get rid of NO_IRQ usage"),
no irq case has been removed, irq_of_parse_and_map() will return
0 in all cases when get error from parse and map an interrupt into
linux virq space.

amba_device_register() is only used on no-DT initialization, see
  s3c64xx_pl080_init()		arch/arm/mach-s3c/pl080.c
  ep93xx_init_devices()		arch/arm/mach-ep93xx/core.c

They won't set -1 to irq[0], so no need the warn.

This reverts commit 2eac58d5.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

drivers/amba/bus.c

@@ -377,9 +377,6 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
 	void __iomem *tmp;
 	int i, ret;
 
-	WARN_ON(dev->irq[0] == (unsigned int)-1);
-	WARN_ON(dev->irq[1] == (unsigned int)-1);
-
 	ret = request_resource(parent, &dev->res);
 	if (ret)
 		goto err_out;