Update set_patch_project_revision to use repo_path_map instead of
patch_projects.
Also rename to set_patch_repo_revision.

Bug: 694348
Change-Id: Iba31f4910f8282160000b8fcef197052597530a4
Reviewed-on: https://chromium-review.googlesource.com/1226107
Commit-Queue: Nodir Turakulov <nodir@chromium.org>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>