[Matrix]: fix a minor problem in unit test of SpMM.
[Matrix]: fix a minor problem in unit test of SpMM.

icoming/FlashX,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashGraph,icoming/FlashGraph,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashGraph,icoming/FlashGraph,icoming/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashX