Revise sm2.test for its wrong refenrence of diff.
Revise sm2.test for its wrong refenrence of diff.

usp-engineers-community/Open-usp-Tukubai,usp-engineers-community/Open-usp-Tukubai,usp-engineers-community/Open-usp-Tukubai,usp-engineers-community/Open-usp-Tukubai