tty: serial/samsung: make register definitions global

The registers for the Samsung S3C serial port are currently defined in
the platform specific arch/arm/plat-samsung/include/plat/regs-serial.h
file, which is not visible to multiplatform capable drivers.

Unfortunately, it is not possible to move the file into a more local
place as we should normally try to, because the same registers
may be used in one of four places:

* In the driver itself
* In platform-independent ARM code for early debug output
* In platform_data definitions
* In the Samsung platform power management code

I have also found no way to logically split out a platform_data
file, other than possibly move everything into
include/linux/platform_data, which also felt wrong. The only
part of this file that makes sense to keep specific to the s3c24xx
platform are the virtual and physical addresses defined here,
which are needed in no other location.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>