Drop unstable pinning of console-setup, console-setup-linux and keyboard-configuration.

On Wheezy, we don't need anything more recent than the stable versions,
so better stick to them.

config/chroot_apt/preferences

@@ -96,18 +96,6 @@ Package: libklibc
 Pin: release o=Debian,n=wheezy
 Pin-Priority: 999
 
-Package: console-setup
-Pin: release o=Debian,a=unstable
-Pin-Priority: 999
-
-Package: console-setup-linux
-Pin: release o=Debian,a=unstable
-Pin-Priority: 999
-
-Package: keyboard-configuration
-Pin: release o=Debian,a=unstable
-Pin-Priority: 999
-
 Package: linux-base
 Pin: release o=Debian,a=unstable
 Pin-Priority: 999