travis: Enable fedora30 for ppc64le

Back in ac734a0 when we added fedora30, we were seeing weird
failures on ppc64le. We no longer see them, so enforce fedora30 passing
there.

Signed-off-by: Stewart Smith <stewart@linux.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

.travis.yml

@@ -27,8 +27,6 @@ matrix:
   allow_failures:
     - env: RUN_ON_CONTAINER=fedora-rawhide
     - env: RUN_ON_CONTAINER=debian-unstable
-    - os: linux-ppc64le
-      env: RUN_ON_CONTAINER=fedora30
   exclude:
     - os: linux-ppc64le
       env: RUN_ON_CONTAINER=centos7