ARM: dts: r8a7779: Correct interrupt type for ARM TWD

The ARM TWD interrupt is a private peripheral interrupt (PPI), and per
the ARM GIC documentation, whether the type for PPIs can be set is
IMPLEMENTATION DEFINED.

For R-Car H1 devices the PPI type cannot be set, and so when we attempt
to set the type for the ARM TWD interrupt it fails.  This has gone
unnoticed because it fails silently, and because we cannot re-configure
the type it has had no impact. Nevertheless fix the type for the TWD
interrupt so that it matches the hardware configuration.

Based on patches by Jon Hunter for Tegra20/30 and OMAP4.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>