hwrng: xgene - add support for APM X-Gene SoC RNG support

Hello Feng Kan,

The patch a91ae4eba9f9: "hwrng: xgene - add support for APM X-Gene SoC RNG support" from Aug 22, 2014, leads to the following static checker warning:

	drivers/char/hw_random/xgene-rng.c:339 xgene_rng_probe()
	warn: unsigned 'ctx->irq' is never less than zero.

drivers/char/hw_random/xgene-rng.c
335 if (IS_ERR(ctx->csr_base))
336 return PTR_ERR(ctx->csr_base);
337
338 ctx->irq = platform_get_irq(pdev, 0);

   339          if (ctx->irq < 0) {
                    ^^^^^^^^^^^^

Impossible for unsigned values.

340 dev_err(&pdev->dev, "No IRQ resource\n");
341 return ctx->irq;
342 }
343
344 dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d",

regards,
dan carpenter