lib: arm_ffa: Add support for MSG_SEND_DIRECT_REQ2 UUID demuxing am: 6b8ec48a27

Original change: https://android-review.googlesource.com/c/trusty/lk/trusty/+/3455924

Change-Id: Id42203916c3f2536c2a24cbd1f9fed67b497e8d6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>