arm64: tegra: Add dma-coherent for Tegra194 VIC

DMA operations for the Tegra194 Video Image Compositor (VIC) are
coherent and so populate the 'dma-coherent' property.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>