[Misc] Update Phi-3-Vision Example (vllm-project#5981)

Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>

examples/phi3v_example.py

@@ -10,16 +10,18 @@
 def run_phi3v():
     model_path = "microsoft/Phi-3-vision-128k-instruct"
 
-    # Note: The model has 128k context length by default which may cause OOM
-    # In this example, we override max_model_len to 2048.
+    # Note: The default setting of max_num_seqs (256) and
+    # max_model_len (128k) for this model may cause OOM.
+    # In this example, we override max_num_seqs to 5 while
+    # keeping the original context length of 128k.
     llm = LLM(
         model=model_path,
         trust_remote_code=True,
         image_input_type="pixel_values",
         image_token_id=32044,
         image_input_shape="1,3,1008,1344",
         image_feature_size=1921,
-        max_model_len=2048,
+        max_num_seqs=5,
     )
 
     image = Image.open("images/cherry_blossom.jpg")