use /usr/lib/cloud/management/systemvm_mnt instead of /mnt/cloud/systemvm.

We should use home dir of user 'cloud', don't do any assumption of umask of /mnt,
it varies from distribution

scripts/vm/systemvm/injectkeys.sh

@@ -27,7 +27,7 @@
 #set -x
 
 TMP=${HOME}/tmp
-MOUNTPATH=/mnt/cloud/systemvm
+MOUNTPATH=${HOME}/systemvm_mnt
 TMPDIR=${TMP}/cloud/systemvm
 
 
@@ -40,6 +40,7 @@ inject_into_iso() {
   local newpubkey=$2
   local backup=${isofile}.bak
   local tmpiso=${TMP}/$1
+  mkdir -p $MOUNTPATH
   [ ! -f $isofile ] && echo "$(basename $0): Could not find systemvm iso patch file $isofile" && return 1
   sudo mount -o loop $isofile $MOUNTPATH 
   [ $? -ne 0 ] && echo "$(basename $0): Failed to mount original iso $isofile" && clean_up && return 1