Use the updated qemu binary to convert the qcow2 image to a vmdk image by running this qemu-img convert command:
qemu-img convert -f qcow2 -O vmdk -o subformat=streamOptimized source_qcow_image_path destination_path_to_vmdk
For example:
qemu-img convert -f qcow2 -O vmdk -o subformat=streamOptimized CentOS-7-x86_64-GenericCloud-1503.qcow2 CentOS-7-x86_64-GenericCloud-1503.vmdk
Update the vmdk version setting embedded in the converted image using this script:
printf '\x03' | dd conv=notrunc of=<vmdk file name> bs=1 seek=$((0x4))
For example:
printf '\x03' | dd conv=notrunc of=CentOS-7-x86_64-GenericCloud-1503.vmdk bs=1 seek=$((0x4))