dt-bindings: iio: adc: exynos-adc: Add S5PV210 variant

[ Upstream commit a9b0a2a7c19316588421b94946c8e2e5a84ac14e ]

Add information about new compatible for S5PV210

Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>