fstab.common: adding options for userdata partition to enable FBE

according to the document here:
    https://source.android.com/security/encryption/file-based

Test: boot up db845c with android-5.4 and android-mainline kernels, and tested with vts-kernel -m VtsKernelEncryptionTest

Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
Change-Id: I6ad25b5fef31bef77893f6d5e267568489116fae
1 file changed