video: tegra: host: use dma APIs for patch ctx

video: tegra: host: use dma APIs for patch ctx

- use dma_alloc/free_attrs() APIs to allocate memory for patch_ctx
  and pass DMA_ATTR_NO_KERNEL_MAPPING attribute to it
- when needed, use vmap() and vunmap() for kernel mappings
- use gk20a_gmmu_map()/unmap() to update gmmu ptes

Bug 1397647

Change-Id: I2be88e0b597f072f20f40ec56ea4bdb08ed36912
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/352251
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Sachin Nikam <snikam@nvidia.com>