gpu: nova-core: gsp: unconditionally call variable payload handling

gpu: nova-core: gsp: unconditionally call variable payload handling

Unconditionally call the variable length payload code, which is a no-op
if there is no such payload but could defensively catch some coding
errors by e.g. checking that the allocated size is completely filled.

Tested-by: Zhi Wang <zhiw@nvidia.com>
Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
Link: https://patch.msgid.link/20260306-cmdq-continuation-v6-6-cc7b629200ee@nvidia.com
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>