gpu: nova-core: add FbHal::frts_size() for GA100 support

gpu: nova-core: add FbHal::frts_size() for GA100 support

Introduce FbHal method frts_size() to return the size of the FRTS
window.  GA100 is a special case in that although there is an
FRTS, its size must arbitrarily be set to 0.

Note that we cannot use supports_display() to determine the FRTS
size because there are other GPUs (e.g. GA102GL) that have display
disabled (and so supports_display() returns False), but the FRTS
window size still needs to be 1MB.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260417191359.1307434-5-ttabi@nvidia.com
[acourbot: apply requested fix to commit message.]
[acourbot: fix minor conflict.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>