Fixes model arguments for amazon models (#5896)

Fixes #5713 
#### Who can review?

Tag maintainers/contributors who might be interested:
@hwchase17
@agola11
@aarora79
@rsgrewal-aws

langchain/llms/bedrock.py

@@ -20,6 +20,10 @@ class LLMInputOutputAdapter:
         input_body = {**model_kwargs}
         if provider == "anthropic" or provider == "ai21":
             input_body["prompt"] = prompt
+        elif provider == "amazon":
+            input_body = dict()
+            input_body["inputText"] = prompt
+            input_body["textGenerationConfig"] = {**model_kwargs}
         else:
             input_body["inputText"] = prompt