debian: Update Vcs-Git to point to launchpad

We're hosting the repo in launchpad now. The kernel.ubuntu.com
repo still works but is just a mirror, so update it to point to
the one we're actually using.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

debian/control

@@ -4,7 +4,7 @@ Priority: optional
 Maintainer: Ubuntu Kernel Team <kernel-team@lists.ubuntu.com>
 Standards-Version: 3.9.6
 Build-Depends: debhelper (>= 4.0.0), rsync
-Vcs-Git: git://kernel.ubuntu.com/ubuntu/linux-firmware.git
+Vcs-Git: git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux-firmware
 
 Package: linux-firmware
 Architecture: all