You could add cryptodev_linux into yocto:tiny rootfs manually, please refer to the following.
1. $ flex-builder -c cryptodev_linux -a arm64
2. $ cd ~/flexbuild_lsdk1909/build/rfs/rootfs_yocto_LS_arm64_tiny/target
$ mkdir -p lib/modules/4.19.68/extra/
$ cp ~/flexbuild_lsdk1909/build/linux/linux/arm64/LS/lib/modules/4.19.68/extra/cryptodev.ko lib/modules/4.19.68/extra/
3. Package yocto:tiny rootfs
$ cd ~/flexbuild_lsdk1909
$ flex-builder -i packrfs -r yocto:tiny -a arm64
