Remove blocked branches

"coverity_scan" branch is been removed as Travis shouldn't be
blocked from triggering it to run Coverity on it.

"development-psa" branch isn't used anymore and also it used to
depend on a private submodule which Travis would fail to get.

.travis.yml

@@ -5,12 +5,6 @@ compiler:
 sudo: false
 cache: ccache
 
-# blocklist
-branches:
-  except:
-  - development-psa
-  - coverity_scan
-
 script:
 - tests/scripts/recursion.pl library/*.c
 - tests/scripts/check-generated-files.sh