CUDA: use fastdiv in set-rows

[am17an]

Helpful in TG

Device 0: NVIDIA GeForce RTX 4090, compute capability 8.9, VMM: yes

Model	Test	t/s master	t/s set-row	Speedup
gpt-oss 20B MXFP4 MoE	tg128	186.10	187.25	1.01
gpt-oss 20B MXFP4 MoE	tg256	184.63	187.19	1.01
gpt-oss 20B MXFP4 MoE	tg512	183.95	184.45	1.00
qwen3moe 30B.A3B Q4_0	tg128	161.55	163.48	1.01
qwen3moe 30B.A3B Q4_0	tg256	162.39	163.33	1.01
qwen3moe 30B.A3B Q4_0	tg512	159.14	160.86	1.01