ARM: S5P6440: Add Touchscreen support for S5P6440

This patch adds touchscreen support for S5P6440.

Signed-off-by: Naveen Krishna Ch <ch.naveen@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
[ben-linux@fluff.org: minor header fix]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>