mfd: pm8921: Fixup probe() error path when irq invalid

platform_get_irq() returns a negative error code when an IRQ is invalid
or unspecified.  Make 'irq' signed to properly handle this.

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/pm8921-core.c

@@ -394,9 +394,8 @@ static int pm8921_probe(struct platform_device *pdev)
 {
 	struct pm8921 *pmic;
 	struct regmap *regmap;
-	int rc;
+	int irq, rc;
 	unsigned int val;
-	unsigned int irq;
 	u32 rev;
 	struct pm_irq_chip *chip;
 	unsigned int nirqs = PM8921_NR_IRQS;