gpu: nova-core: move GFW boot wait into a GPU HAL

gpu: nova-core: move GFW boot wait into a GPU HAL

Introduce a GpuHal trait and per-family dispatch so GPU boot
behavior can vary by architecture. Move wait_gfw_boot_completion()
from the standalone gfw module into gpu/hal/tu102.rs as the first
GpuHal implementation. All architectures currently dispatch to this
implementation, preserving existing behavior.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260411024953.473149-7-jhubbard@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>