tty/serial: samsung: enable usage for 64-bit Exynos platforms

Allow Samsung serial driver to be usable on Exynos 64-bit SoC based
platforms.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>