iio: light: us5182d: Fix enable status inconcistency

When setting als only or proximity only modes make sure that we mark the
other component as disabled. This fix is in preparation of adding event
support because that will make it possible to switch between one-shot and
continuous modes and not tracking these correctly may cause faulty
behaviour (e.g wrongfully considering px enabled and not setting an
appropriate mode in the chip).

Signed-off-by: Adriana Reus <adriana.reus@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>