Remove forgotten LinuxMint occurrence

Right now we don't officialy support LinuxMint as our
documentation says [1], it seems LinuxMint is a relict
and got forgotten over time.

This patch removes LinuxMint from the code in order not to
confuse users.

[1] https://docs.openstack.org/devstack/latest/
Closes-Bug: #1983427

Change-Id: Ie1ced25f89389494b28a7b2e9bb1c4273e002dd5
diff --git a/functions-common b/functions-common
index e5b0751..92a6678 100644
--- a/functions-common
+++ b/functions-common
@@ -426,7 +426,7 @@
         os_VENDOR=$(lsb_release -i -s)
     fi
 
-    if [[ $os_VENDOR =~ (Debian|Ubuntu|LinuxMint) ]]; then
+    if [[ $os_VENDOR =~ (Debian|Ubuntu) ]]; then
         os_PACKAGE="deb"
     else
         os_PACKAGE="rpm"
@@ -444,9 +444,8 @@
 
 function GetDistro {
     GetOSVersion
-    if [[ "$os_VENDOR" =~ (Ubuntu) || "$os_VENDOR" =~ (Debian) || \
-            "$os_VENDOR" =~ (LinuxMint) ]]; then
-        # 'Everyone' refers to Ubuntu / Debian / Mint releases by
+    if [[ "$os_VENDOR" =~ (Ubuntu) || "$os_VENDOR" =~ (Debian) ]]; then
+        # 'Everyone' refers to Ubuntu / Debian releases by
         # the code name adjective
         DISTRO=$os_CODENAME
     elif [[ "$os_VENDOR" =~ (Fedora) ]]; then