gpu: nova-core: add FalconUCodeDescV2 support

gpu: nova-core: add FalconUCodeDescV2 support

The FRTS firmware in Turing and GA100 VBIOS has an older header
format (v2 instead of v3).  To support both v2 and v3 at runtime,
add the FalconUCodeDescV2 struct, and update code that references
the FalconUCodeDescV3 directly with a FalconUCodeDesc enum that
encapsulates both.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260122222848.2555890-11-ttabi@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>