pinctrl: microchip-sgpio: Correct the fwnode_irq_get() return value check

fwnode_irq_get() may return all possible signed values, such as Linux
error code. Fix the code to handle this properly.

Fixes: be2dc859 ("pinctrl: pinctrl-microchip-sgpio: Add irq support (for sparx5)")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220906115021.8661-1-andriy.shevchenko@linux.intel.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-microchip-sgpio.c

@@ -864,9 +864,10 @@ static int microchip_sgpio_register_bank(struct device *dev,
 	gc->can_sleep		= !bank->is_input;
 
 	if (bank->is_input && priv->properties->flags & SGPIO_FLAGS_HAS_IRQ) {
-		int irq = fwnode_irq_get(fwnode, 0);
+		int irq;
 
-		if (irq) {
+		irq = fwnode_irq_get(fwnode, 0);
+		if (irq > 0) {
 			struct gpio_irq_chip *girq = &gc->irq;
 
 			gpio_irq_chip_set_chip(girq, &microchip_sgpio_irqchip);