iio: light: jsa1212: remove unneeded i2c check functionality test

This driver does not call i2c_smbus_read|write_byte_data(),
so remove the corresponding functionality test. It uses regmap
to handle byte transfers transparently.

Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Matt Ranostay <matt.ranostay@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>