[RVV] Add missing maxpool and avgpool rvv kernels

[ken-unger]

• Add rvv script to generate f32-avgpool and f16-avgpool rvv kernels
• Rewrite rvv script to generate f32-maxpool and add f16-maxpool, s8-maxpool, u8-maxpool rvv kernels
• Script now closely follows the simd version.

Relevant tests and benchmarks executed and pass (BPI-F3).

[ken-unger]

RE: rvv hardware detection support for fp16

@dsharlet just fyi, I've opened a PR in pytorch/cpuinfo for this purpose. Once that is reviewed and merged I can make the needed changes to hardware-config.c. pytorch/cpuinfo#375

While other changes in cpuinfo are desirable (e.g cache info for riscv uarchs) I tried to keep the changes to a minimum this round in the hope that the review goes smoothly.

[ken-unger]

@fbarchard please also give this PR a lookover when you have a few minutes. Thank you.

[ken-unger]

@fbarchard could you review when you have a few free minutes. Thank you.

[ken-unger]

@dsharletg I've updated this PR to latest master and retested. Please review and merge when you are able. Thank you!

With this, subgraph-mobilenet-bench now runs with the FP16 datatype.

2026-04-13T14:19:40-07:00
Running subgraph-mobilenet-bench
Run on (8 X 1600 MHz CPU s)
CPU Caches:
  L1 Instruction 32 KiB (x8)
  L1 Data 32 KiB (x8)
  L2 Unified 512 KiB (x2)
Load Average: 2.63, 2.47, 1.48
***WARNING*** ASLR is enabled, the results may have unreproducible noise in them.
------------------------------------------------------------------------------------------------------
Benchmark                                            Time             CPU   Iterations UserCounters...
------------------------------------------------------------------------------------------------------
FP32MobileNetV1/process_time/real_time          186104 us       186098 us            4 cpufreq=1.6G
FP32MobileNetV2/process_time/real_time          185933 us       185941 us            4 cpufreq=1.6G
FP32MobileNetV3Large/process_time/real_time     224285 us       224279 us            3 cpufreq=1.6G
FP32MobileNetV3Small/process_time/real_time      72538 us        72547 us           10 cpufreq=1.6G
FP16MobileNetV1/process_time/real_time          112145 us       112153 us            7 cpufreq=1.6G
FP16MobileNetV2/process_time/real_time           91548 us        91556 us            8 cpufreq=1.6G
FP16MobileNetV3Large/process_time/real_time      75921 us        75930 us            9 cpufreq=1.6G
FP16MobileNetV3Small/process_time/real_time      25811 us        25821 us           27 cpufreq=1.6G
QS8MobileNetV2/process_time/real_time            54616 us        54625 us           13 cpufreq=1.6G

[ken-unger]

@dsharletg thank you for all the previous PR approvals and merges. A very friendly ping on this one. I think we (or at least I) are getting very close to done.