add md_zmul2 benchmark
add md_zmul2 benchmark

Takishima/bart,mrirecon/bart,mrirecon/bart,sdimoudi/bart,sdimoudi/bart,Takishima/bart,mrirecon/bart,sdimoudi/bart,sidward/bart,sdimoudi/bart,mrirecon/bart,sidward/bart,Takishima/bart,Takishima/bart,sdimoudi/bart,sidward/bart,sidward/bart,sidward/bart,Takishima/bart,mrirecon/bart