Don't repeatedly try to install amd64 kernel

src/freedombone-utils-setup

@@ -203,7 +203,10 @@ function install_backports_kernel {
     architecture_type=$(uname -a)
 
     if [[ "$architecture_type" == *"amd64"* ]]; then
-        apt-get -yq install linux-image-amd64
+        package_installed=$(dpkg-query -W -f='${Package}\n' linux-image-amd64 2>/dev/null)
+        if [ ! $package_installed ]; then
+            apt-get -yq install linux-image-amd64
+        fi
     fi
 }