Compatible with Kneron PLUS 2

The Kneron PLUS 2 provides include/legacy/kp_inference_v1.h and include/legacy/kp_struct_v1.h for temporary backward compatibility with V1.x APIs. The legacy code can be easily migrated to Kneron PLUS 2 by changing the include header.

For example, the V1.x basic include header can be rewritten like the following code block. (For more examples, please reference sample code in kneron_plus/examples_legacy)