Prepare Function Unit and Registers for mapping

[tancheng]

Prepare the Function Unit and Registers for mapping. A tile could contain registers and functional units

• hierarchi: Tile -> Register File Cluster -> Register File -> Register, [P1] Assign/model registers in tile #81
• @Jackcuii I have prototyped the Function Unit for you, please honor the arch spec to initialize them, TODO with @Jackcuii are left as comments, [P1] Agreement on PE Behavior Representation #82 [P1] Model dataflow accelerator based on specs #52

TODO:

• Relax the mapping constraint on the input channel by moving data from the channel to local registers
  • Register might also be modeled in MRRG, [P1] Assign/model registers in tile #81