tty: serial: samsung_tty: Add ucon_mask parameter

This simplifies the code by removing the only distinction between the
S3C2410 and S3C2440 codepaths.

Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Tested-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210304213902.83903-20-marcan@marcan.st


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>