Enable F22 without the FORCE flag

F22 has a stable release and working with devstack.

The change also removes the version flags regarding to the
mariadb-devel.

NOTE: You may see yum deprecation warnings, unless
you set the YUM variable to dnf.

Change-Id: I05140765bffc16faef5a29dfaba291c290bfae02

files/rpms/devlibs

@@ -1,8 +1,7 @@
 libffi-devel  # pyOpenSSL
 libxml2-devel  # lxml
 libxslt-devel  # lxml
-mariadb-devel  # MySQL-python  f20,f21,rhel7
-mysql-devel  # MySQL-python  rhel6
+mariadb-devel  # MySQL-python
 openssl-devel  # pyOpenSSL
 postgresql-devel  # psycopg2
 python-devel  # pyOpenSSL