util: Fix bookkeeping of linear node sizes

When creating a new node, we were clobbering the original size
requested, and use that as offset, so the node would always be full.

Fixes: 591db9a9a54 ("util: Remove per-buffer header in linear alloc for release mode")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25382>
1 file changed