hwmon: (w83781d) Fix W83782D support (NULL pointer dereference)

Commit 360782dde00a2e6e7d9fd57535f90934707ab8a8 (hwmon: (w83781d) Stop
abusing struct i2c_client for ISA devices) broke W83782D support for
devices connected on the ISA bus. You will hit a NULL pointer
dereference as soon as you read any device attribute. Other devices,
and W83782D devices on the SMBus, aren't affected.

Reported-by: Michel Abraham
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Michel Abraham

drivers/hwmon/w83781d.c

@@ -1462,7 +1462,8 @@ static struct w83781d_data *w83781d_update_device(struct device *dev)
 				data->pwm[i] =
 				    w83781d_read_value(data,
 						       W83781D_REG_PWM[i]);
-				if ((data->type != w83782d || !client->driver)
+				/* Only W83782D on SMBus has PWM3 and PWM4 */
+				if ((data->type != w83782d || !client)
 				    && i == 1)
 					break;
 			}