ARM: s3c: adc: move header to linux/soc/samsung

ARM: s3c: adc: move header to linux/soc/samsung

There are multiple drivers using the private adc interface.
It seems unlikely that they would ever get converted to iio,
so make the current state official by making the header file
global.

The s3c2410_ts driver needs a couple of register definitions
as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Sebastian Reichel <sre@kernel.org>
Link: https://lore.kernel.org/r/20200806182059.2431-22-krzk@kernel.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>