[Matrix]: fix a bug of getting the sparse matrix ele type.
[Matrix]: fix a bug of getting the sparse matrix ele type.

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