[api] Remove unnecessary intermediate variable in frame helpers (#11668)

esphome/components/api/api_frame_helper_noise.cpp

@@ -434,8 +434,7 @@ APIError APINoiseFrameHelper::write_protobuf_packets(ProtoWriteBuffer buffer, st
     return APIError::OK;
   }
 
-  std::vector<uint8_t> *raw_buffer = buffer.get_buffer();
-  uint8_t *buffer_data = raw_buffer->data();  // Cache buffer pointer
+  uint8_t *buffer_data = buffer.get_buffer()->data();
 
   this->reusable_iovs_.clear();
   this->reusable_iovs_.reserve(packets.size());

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -230,8 +230,7 @@ APIError APIPlaintextFrameHelper::write_protobuf_packets(ProtoWriteBuffer buffer
     return APIError::OK;
   }
 
-  std::vector<uint8_t> *raw_buffer = buffer.get_buffer();
-  uint8_t *buffer_data = raw_buffer->data();  // Cache buffer pointer
+  uint8_t *buffer_data = buffer.get_buffer()->data();
 
   this->reusable_iovs_.clear();
   this->reusable_iovs_.reserve(packets.size());