gpu: nova-core: vbios: construct `FwSecBiosImage` directly from BIOS images

gpu: nova-core: vbios: construct `FwSecBiosImage` directly from BIOS images

`FwSecBiosBuilder` now only contains `falcon_ucode_offset` which just
gets passed directly into `FwSecBiosImage`. Remove `FwSecBiosBuilder`
and construct `FwSecBiosImage` directly, as a simplification.

Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Link: https://patch.msgid.link/20260525-fix-vbios-v5-14-e5e455251537@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>