broadcom/compiler: always restart ldvary pipelining when scheduling ldvary

When we were only able to pipeline smooth varyings, if we had to disable ldvary pipelining in the middle of a sequence it would stay disabled for the rest of the program, to prevent us from prioritizing scheduling of ldvary instructions that we would not be able to pipeline effectively. Now that we can pipeline all ldvary sequences we can change this.

This change re-enables ldvary pipelining upon finding the next ldvary in the program in the hopes that we can continue pipelining succesfully. To do this, we track the number of ldvary instructions we emitted so far and compare that to the number of inputs in the fragment shader we are scheduling. This also allows us to simplify our ldvary tracking at nir to vir time, since that is all now handled in the QPU scheduler.

total instructions in shared programs: 13817048 -> 13810783 (-0.05%)
instructions in affected programs: 810114 -> 803849 (-0.77%)
helped: 4843
HURT: 591
Instructions are helped.

total max-temps in shared programs: 2326612 -> 2326300 (-0.01%)
max-temps in affected programs: 4689 -> 4377 (-6.65%)
helped: 285
HURT: 7
Max-temps are helped.

total sfu-stalls in shared programs: 30942 -> 30865 (-0.25%)
sfu-stalls in affected programs: 207 -> 130 (-37.20%)
helped: 120
HURT: 42
Sfu-stalls are helped.

total inst-and-stalls in shared programs: 13847990 -> 13841648 (-0.05%)
inst-and-stalls in affected programs: 825378 -> 819036 (-0.77%)
helped: 4899
HURT: 590
Inst-and-stalls are helped.