ARM: dts: ux500: Fix touchscreen on TVK R2

The touchscreen is mounted with flipped x/y on the R2
version of TVK1281618. Push this setting to that DTS file
only.

The function nodes were named wrong so the OF properties
didn not "take". Fix the node names from "rmi-fnn" to
"rmi4-nn" so this also work.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>