freedreno/ir3: Enable the i/o vectorizer on UBOs.

freedreno/ir3: Enable the i/o vectorizer on UBOs.

This will merge loads of UBO components together into vec4 loads.  At the
same time, it improves the alignment information on our loads, fixing the
regression from the vec3 loads fix.

shader-db results:
total instructions in shared programs: 12829370 -> 8755851 (-31.75%)
total cat6 in shared programs: 145840 -> 97027 (-33.47%)

Overall results from before the vec3 fix:
total instructions in shared programs: 8019997 -> 8755851 (9.18%)
total cat6 in shared programs: 87683 -> 97027 (10.66%)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6612>