drm/nouveau/instmem: add hal for set_bar0_window_addr()

GH100/GBxxx have moved the register that controls where in VRAM the
the BAR0 NV_PRAMIN window points.

Add a HAL for this, as the BAR0 window is needed for BAR2 bootstrap.

Signed-off-by: Ben Skeggs <bskeggs@nvidia.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Timur Tabi <ttabi@nvidia.com>
Tested-by: Timur Tabi <ttabi@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>