dt-bindings: media: Correct camss supply description

dt-bindings: media: Correct camss supply description

Usually, the supply is around 1.2 V, not 1.8 V, and also correct wording.

Signed-off-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>