Move trusty reference implementations to /vendor

Trusty implementations are provided by vendors. This patch moves
the AOSP reference implementations to the vendor partition.

Bug: 63085384
Test: build gordon_peak which adopts trusty as the TEE and confirm
      that libtrusty and gateway.trusty are moved to /vendor.
Test: build marlin which does not adopt trusty as the TEE and confirm
      that this patch has no effect on the build result.
Change-Id: I9a5440071386b929058207fdef560ed2d7223ba3