fastmodel: Implement Iris::MMU::translateFunctional.
fastmodel: Implement Iris::MMU::translateFunctional.

This new pure virtual method was not implemented, preventing the
automatic create() method from being generated, and causing a linking
error.

Change-Id: I5619da5216d5161cb5e227de627b02f395bea0e9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52705
Maintainer: Gabe Black <d3e8afea784ab4a50a2dbf9149d2eaa8478e1cbc@gmail.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Earl Ou <82591a79653dd29c9ce06ea2b578447596bef9ab@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5