vbo/dlist: convert LINE_STRIPS to LINES
Less primitive modes allows for better primitive merging. Lines are always used (instead of picking dynamically lines or line strips for instance) because: - they don't need primitive restarts to be merged - they perform better (at least on radeonsi) - SPECviewperf13 snx subtests with lines (like 4 or 10) are 1.5x-2x faster. Reviewed-by:Marek Olšák <marek.olsak@amd.com> Part-of: <mesa/mesa!7078>