iio: light: tcs3414: Fix bug preventing to set integration time

the millisecond values in tcs3414_times should be checked against
val2, not val, which is always zero.

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Reported-by: Stephan Kleisinger <stephan.kleisinger@gmail.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>