staging:iio:light:tsl2583 allocate chip state with iio_dev

There are some unusual corners in the probe function of this
driver, so may need another look.

V2: Now with the check for allocation success not inverted.
V3: Now with the i2c devdata calls actually being correctly cast.
Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Tested-by: Jon Brenner <jbrenner@TAOSinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>