gpu: nova-core: gsp: replace ARef<Device> with &'a Device in sequencer

gpu: nova-core: gsp: replace ARef<Device> with &'a Device in sequencer

GspSequencer, GspSeqIter, and GspSequencerParams are already
lifetime-parameterized; the ARef<Device> is unnecessary -- a plain
&'a Device reference suffices.

Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260525225838.276108-5-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>