FROMGIT: of: Add plumbing for restricted DMA pool

If a device is not behind an IOMMU, we look up the device node and set
up the restricted DMA when the restricted-dma-pool is presented.

Signed-off-by: Claire Chang <tientzu@chromium.org>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Tested-by: Will Deacon <will@kernel.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
(cherry picked from commit fec9b625 swiotlb/devel/for-linus-5.15)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 190591509
Change-Id: I020491ccb781528e8fd8d286acbc56b11f136634