[HACK] mfd: tps65086: make interrupt line optional

The BeagleV Starlight v0.9 board doesn't have the IRQB line from the
pmic routed to the SoC, so this hack is needed to allow the driver
to be loaded without it. See
beagleboard/beaglev-starlight#14

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>

drivers/mfd/tps65086.c

@@ -100,11 +100,13 @@ static int tps65086_probe(struct i2c_client *client,
 		 (char)((version & TPS65086_DEVICEID_OTP_MASK) >> 4) + 'A',
 		 (version & TPS65086_DEVICEID_REV_MASK) >> 6);
 
-	ret = regmap_add_irq_chip(tps->regmap, tps->irq, IRQF_ONESHOT, 0,
-				  &tps65086_irq_chip, &tps->irq_data);
-	if (ret) {
-		dev_err(tps->dev, "Failed to register IRQ chip\n");
-		return ret;
+	if (tps->irq > 0) {
+		ret = regmap_add_irq_chip(tps->regmap, tps->irq, IRQF_ONESHOT, 0,
+					  &tps65086_irq_chip, &tps->irq_data);
+		if (ret) {
+			dev_err(tps->dev, "Failed to register IRQ chip\n");
+			return ret;
+		}
 	}
 
 	ret = mfd_add_devices(tps->dev, PLATFORM_DEVID_AUTO, tps65086_cells,