gpu: nova-core: gsp: run the unload bundle if Gsp::boot() fails

gpu: nova-core: gsp: run the unload bundle if Gsp::boot() fails

If `Gsp::boot` fails, the GSP can be left in a state where boot cannot
be attempted again unless it is reset first.

To avoid this, we want to run the unload bundle whenever `boot` fails to
try and clear the partially-initialized state.

Do this by wrapping the unload bundle into a drop guard up until `boot`
returns. After that, running the unload bundle becomes the
responsibility of the caller.

Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Eliot Courtney <ecourtney@nvidia.com>
Link: https://patch.msgid.link/20260529-nova-unload-v7-4-678f39209e00@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>