mfd: stmpe: DT: Enable no-irq mode configuration

If there is no interrupt property into stmpe node
then activate the no-irq mode by setting the irq
value to -1.

Cc: devicetree-discuss@lists.ozlabs.org
Signed-off-by: NGabriel Fernandez <gabriel.fernandez@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/mfd/stmpe.c

@@ -1057,6 +1057,9 @@ int stmpe_probe(struct stmpe_client_info *ci, int partnum)
 			return -ENOMEM;
 
 		stmpe_of_probe(pdata, np);
+
+		if (of_find_property(np, "interrupts", NULL) == NULL)
+			ci->irq = -1;
 	}
 
 	stmpe = devm_kzalloc(ci->dev, sizeof(struct stmpe), GFP_KERNEL);