Bump default image-size

Only the L5 can currently cope with a smaller image since it
get not devtools. This unbreaks the devkit byzantium build.

build-image

@@ -168,7 +168,7 @@ meta_yml=files/meta.yml
 fk_machine=
 JENKINS_AUTH=()
 # in Megabytes
-image_size=4100
+image_size=4500
 passphrase=""
 
 while getopts ":hb:d:T:Bl:" opt; do

conf/board

@@ -188,7 +188,6 @@ case ${pureos_board} in
     board_packages="
         librem5-dev-tools
     "
-    image_size=4500
     ;;
   *)
     echo "unrecognized board type ${pureos_board}"