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>