project/qemu: Use FIND_EXTERNAL macro for some externals

The Linux kernel, qemu, and TF-A are moving to external/trusty.
Use the new FIND_EXTERNAL macro to locate them in a backwards
compatible way from either the old or new directory.

Bug: 230135749
Test: presubmit
Change-Id: Ie0b675f9dc475f38277fe423e1151cf038f7b7bf
3 files changed
tree: 700757bc7bc394fe1828e97869d8d65b753f5514
  1. project/
  2. .clang-format
  3. LICENSE
  4. PREUPLOAD.cfg