Input: tnetv107x-keypad - make irqs signed for error handling

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

	kp->irq_press   = platform_get_irq_byname(pdev, "press");
	kp->irq_release = platform_get_irq_byname(pdev, "release");
	if (kp->irq_press < 0 || kp->irq_release < 0) {

The problem is that these irq variables are unsigned so the error
handling doesn't work.  I've changed them to signed values.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>