gpu: nova-core: prepare Spec and Revision types for boot0/boot42

gpu: nova-core: prepare Spec and Revision types for boot0/boot42

Allow a both Revision and Spec to be constructed directly from a
NV_PMC_BOOT_0 register.

Also, slightly enhance the comment about Spec, to be more precise.

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251115010923.1192144-2-jhubbard@nvidia.com>