ARM: dts: ux500: Split TVK DTSI files in two

The TVK1281618 was made in R1, R2 and R3 variants. The most
commonly used variants are R2 and R3 so split out these to
their own files.

The R3 version has a totally different display than R1 and
R2 and a different set of sensors.

Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20191126124738.77690-2-linus.walleij@linaro.org