freedreno/ir3: Stop shifting UBO 1 down to be UBO 0.

freedreno/ir3: Stop shifting UBO 1 down to be UBO 0.

It turns out the GL uniforms file is larger than the hardware constant
file, so we need to limit how many UBOs we lower to constbuf loads.  To do
actual UBO loads, we'll need to be able to upload UBO 0's pointer or
descriptor.

No difference on nohw 1 UBO update drawoverhead case (n=35).

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5273>