linux-imx

habanalabs: add MMU shadow mapping

This patch adds shadow mapping to the MMU module. The shadow mapping
allows traversing the page table in host memory rather reading each PTE
from the device memory.
It brings better performance and avoids reading from invalid device
address upon PCI errors.
Only at the end of map/unmap flow, writings to the device are performed in
order to sync the H/W page tables with the shadow ones.

Signed-off-by: Omer Shpigelman <oshpigelman@habana.ai>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>