ARM: s3c: simplify platform code

Following down the now unused symbols and header files, some additional
content can be dropped that is used by neither the s3c64xx DT support
nor the crag6410 board.

Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

ARM: s3c: make headers local if possible

A lot of header files are only used internally now, so they can be moved
to mach-s3c, out of the visibility of drivers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20200806182059.2431-40-krzk@kernel.org
[krzk: Rebase and fixup leds-s3c24xx driver]
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>