[Kernel] Migrate scattered quantization kernels to sglang.kernels (RFC #29630, Phase 2.5, 1/7) (#30784)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

benchmark/kernels/deepseek/benchmark_deepgemm_fp8_gemm_blackwell.py

@@ -7,7 +7,7 @@ from deep_gemm import ceil_div
 from flashinfer.gemm import gemm_fp8_nt_groupwise
 
 from sglang.benchmark.bench_utils import run_bench
-from sglang.srt.layers.quantization.fp8_kernel import (
+from sglang.kernels.ops.quantization.fp8_kernel import (
     sglang_per_token_group_quant_fp8,
     w8a8_block_fp8_matmul_deepgemm,
 )