drm: samsung: move the uapi headers here and add headers_install

These headers were previously in gs/google-modules/raviole-device. Move
them here so that the display driver developers can easily maintain
them. Also add the headers_install target so that they get installed.

Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: I507272b411a9276afeb9d1b5ab79deda43d3a5cd