util: fix util_is_vbo_upload_ratio_too_large

util: fix util_is_vbo_upload_ratio_too_large

It was wrong. For example, if the draw vertex count was 10 and the upload
vertex count was 150, u_vbuf wouldn't unroll the draw and would instead
memcpy 150 vertices. This fixes that case.

Fixes: 068a3bf0d7c - util: move and adjust the vertex upload heuristic equation from u_vbuf

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20824>
(cherry picked from commit 4f6e7858762a38fd7f2e4ab568fc018b4b155f86)