gpio: msm: make msm_gpio.summary_irq signed for error handling

gpio: msm: make msm_gpio.summary_irq signed for error handling

There is a bug in msm_gpio_probe() where we do:

	msm_gpio.summary_irq = platform_get_irq(pdev, 0);
	if (msm_gpio.summary_irq < 0) {

The problem is that "msm_gpio.summary_irq" is unsigned so the error
handling doesn't work.  I've fixed it by making it signed.

Fixes: 43f68444bce7 ('gpio: msm: Add device tree and irqdomain support for gpio-msm-v2')
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>