Add an option for 2048bit dhparams

src/freedombone-sec

       trap "rm -f $data" 0 1 2 5 15
       dialog --backtitle "Freedombone Security Configuration" \
              --title "Diffie-Hellman key length" \
-             --radiolist "The smaller length is better suited to low power embedded systems:" 10 40 2 \
+             --radiolist "The smaller length is better suited to low power embedded systems:" 12 40 3 \
              1 "1024 bits" off \
-             2 "3072 bits" on 2> $data
+             2 "2048 bits" on \
+             3 "3072 bits" off 2> $data
       sel=$?
       case $sel in
           1) exit 1;;
       esac
       case $(cat $data) in
           1) DH_KEYLENGTH=1024;;
-          2) DH_KEYLENGTH=3072;;
+          2) DH_KEYLENGTH=2048;;
+          3) DH_KEYLENGTH=3072;;
       esac
 
       ctr=0