iio: light sensor: Fix a panic in the tsl2563 driver.

Add the required read/write_raw functions to the tsl2563_info_no_irq data
structure.  This structure is used insted of tsl2563_info when the I2C client
has no IRQ.
The absence of these functions causes a panic when reading or writing the
created sysfs files.
Signed-off-by: Bryan Freed <bfreed@chromium.org>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/light/tsl2563.c

@@ -691,6 +691,8 @@ static struct i2c_driver tsl2563_i2c_driver;
 
 static const struct iio_info tsl2563_info_no_irq = {
 	.driver_module = THIS_MODULE,
+	.read_raw = &tsl2563_read_raw,
+	.write_raw = &tsl2563_write_raw,
 };
 
 static const struct iio_info tsl2563_info = {