gpu: nova-core: select RUST_FW_LOADER_ABSTRACTIONS

gpu: nova-core: select RUST_FW_LOADER_ABSTRACTIONS

RUST_FW_LOADER_ABSTRACTIONS was depended on by NOVA_CORE, but NOVA_CORE
is selected by DRM_NOVA. This creates a situation where, if DRM_NOVA is
selected, NOVA_CORE gets enabled but not RUST_FW_LOADER_ABSTRACTIONS,
which results in a build error.

Since the firmware loader is an implementation detail of the driver, it
should be enabled along with it, so change the "depends on" to a
"select".

Fixes: 54e6baf123fd ("gpu: nova-core: add initial driver stub")
Closes: https://lore.kernel.org/oe-kbuild-all/202512061721.rxKGnt5q-lkp@intel.com/
Tested-by: Alyssa Ross <hi@alyssa.is>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20251106-b4-select-rust-fw-v3-2-771172257755@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>