TRTLLM Gen MLA Decode Kernel Integration (same as #7938) (#8632)

Signed-off-by: Faraz Khoubsirat <58580514+farazkh80@users.noreply.github.com>

docs/backend/attention_backend.md

@@ -9,8 +9,12 @@
 | **Triton**               | ❌                | ✅                 | ✅      | ✅                 | ❌              |
 | **Torch Native**         | ❌                | ❌                 | ❌      | ❌                 | ❌              |
 | **FlashMLA**             | ✅                | ✅                 | ✅      | ❌                 | ❌              |
+| **TRTLLM MLA**           | ✅                | ❌                 | ✅      | ✅                 | ❌              |
 | **Ascend**               | ✅                | ❌                 | ❌      | ❌                 | ❌              |
 
+**Notes:**
+- TRTLLM MLA only implements decode operations. For prefill operations (including multimodal inputs), it falls back to FlashInfer MLA backend.
+
 Note: Every kernel backend is compatible with a page size > 1 by specifying an argument such as `--page-size 16`.
 This is because a page size of 16 can be converted to a page size of 1 in the kernel backend.
 The "❌" and "✅" symbols in the table above under "Page Size > 1" indicate whether the kernel actually operates with a page size greater than 1, rather than treating a page size of 16 as a page size of 1.
@@ -48,6 +52,11 @@ python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attenti
 python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attention-backend flashmla --kv-cache-dtype fp8_e4m3 --trust-remote-code
 ```
 
+- TRTLLM MLA (Optimized for Blackwell Architecture, e.g., B200)
+```bash
+python3 -m sglang.launch_server --tp 8 --model deepseek-ai/DeepSeek-R1 --attention-backend trtllm_mla --trust-remote-code
+```
+
 - Ascend
 ```bash
 python3 -m sglang.launch_server --model meta-llama/Meta-Llama-3.1-8B-Instruct --attention-backend ascend