[PATCH v2] riscv/fence: Consolidate fence definitions and define __{mb,rmb,wmb}

[Eric Chan]

Hi Andrea,

  Thank you for reviewing my patch! I appreciate the feedback.
  Referring to your suggestions, the final result is as follows:
    1/4 - riscv/barrier: Define __{mb,rmb,wmb}
    2/4 - riscv/barrier: Define RISCV_FULL_BARRIER
    3/4 - riscv/barrier: Consolidate fence definitions
    4/4 - riscv/barrier: Resolve checkpath.pl error

  I've updated patch v3[https://marc.info/?l=linux-kernel&m=170783431129245]
  Please let me know if you have any further questions or suggestions.

Sincerely,
  Eric Chan