Since Ozone supports external target only
for images created with EGL_EXT_image_dma_buf_import

Bug: 914146, angleproject:2507
Change-Id: I454b26bbb7aa8ed638045dc0c9c98065c9ed76e4
Reviewed-on: https://chromium-review.googlesource.com/c/1374269Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>