defconfig: msm8994: set PFT as the chosen LSM

Currently there is no chosen LSM
and the default empty stub hooks are used.
Until SElinux is enabled, set PFT as the chosen LSM
to allow Per-File-Encryption feature.

Change-Id: I672c8583f7dfe81804a94eedf7a20ae0919a488b
Signed-off-by: Amir Samuelov <amirs@codeaurora.org>