ARM: S3C24XX: serial: Fix section mismatch warnings

During kernel build process, the following warning was found:

WARNING: drivers/serial/built-in.o(.data+0x304): Section mismatch in reference from
the variable s3c2440_serial_drv to the function .devexit.text:s3c24xx_serial_remove()
The variable s3c2440_serial_drv references the function __devexit s3c24xx_serial_remove()
If the reference is valid then annotate the variable with
__exit* (see linux/init.h) or name the variable:
*driver, *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,

The same warning happened for s3c241x platform. We rename variables to avoid
these warnings. These changes also apply to s3c2400 & s3c24a0 for consistency.

Signed-off-by: Ramax Lo <ramaxlo@gmail.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>