gpu: nova: require little endian

gpu: nova: require little endian

The driver already assumes little endian in a lot of locations. For
example, all the code that reads RPCs out of the command queue just
directly interprets the bytes.

Make this explicit in Kconfig.

Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: https://patch.msgid.link/20260407-fix-kconfig-v2-1-6b4fb06c690c@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>