Remove support for End Of Life (EOL) Fedora 22

Fedora 22 reaches its EOL on 19-JUL-2016[1].  Remove it as
officially supported distribution.

The current two supported Fedora distributions are Fedora 23 and Fedora
24.  (Change Ia4a58de4973ef228735c48b33453a0562dc65258 already added
support for Fedora 24.)

[1] https://fedoramagazine.org/fedora-22-end-of-life-2016-july/

Change-Id: I5b4e1ddb6165a9065e80e84175246678a7356f18
diff --git a/lib/ceph b/lib/ceph
index e999647..0c8d160 100644
--- a/lib/ceph
+++ b/lib/ceph
@@ -116,7 +116,7 @@
 
 # check_os_support_ceph() - Check if the operating system provides a decent version of Ceph
 function check_os_support_ceph {
-    if [[ ! ${DISTRO} =~ (trusty|f22|f23|f24) ]]; then
+    if [[ ! ${DISTRO} =~ (trusty|f23|f24) ]]; then
         echo "WARNING: your distro $DISTRO does not provide (at least) the Firefly release. Please use Ubuntu Trusty or Fedora 20 (and higher)"
         if [[ "$FORCE_CEPH_INSTALL" != "yes" ]]; then
             die $LINENO "If you wish to install Ceph on this distribution anyway run with FORCE_CEPH_INSTALL=yes"