lxc-create: fix error with lvm

when --lvname is given, use that for lvcreate instead of using
lxc_name, which is wrong.

Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

src/lxc/lxc-create.in

@@ -237,7 +237,7 @@ fi
 # Create the fs as needed
 mkdir $rootfs
 if [ $backingstore = "lvm" ]; then
-    lvcreate -L $fssize -n $lxc_name $vgname || exit 1
+    lvcreate -L $fssize -n $lvname $vgname || exit 1
     udevadm settle
     mkfs -t $fstype $rootdev || exit 1
     mount -t $fstype $rootdev $rootfs