drm/nouveau/gsp: fix mismatched alloc/free for kvmalloc()

Replace kfree() with kvfree() for memory allocated by kvmalloc().

Compile-tested only.

Cc: stable@vger.kernel.org
Fixes: 8a8b1ec5 ("drm/nouveau/gsp: split rpc handling out on its own")
Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Timur Tabi <ttabi@nvidia.com>
Acked-by: Zhi Wang <zhiw@nvidia.com>
Link: https://lore.kernel.org/r/20250813125412.96178-1-rongqianfeng@vivo.com


Signed-off-by: Danilo Krummrich <dakr@kernel.org>