UBUNTU: [Packaging] Move and update signature inclusion list

BugLink: https://bugs.launchpad.net/bugs/1642368

Move the signature inclusion list from the source tree to the debian/
directory to keep the upstream source clean. While at it, remove modules
that are no longer in the staging area.

Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

debian/signature-inclusion

@@ -2,13 +2,6 @@
 # This file lists the staging drivers that are safe for signing
 # and loading in a secure boot environment with signed module enforcement.
 #
-exfat.ko
-rtl8192c-common.ko
-rtl8192ce.ko
-rtl8192cu.ko
-rtl8192de.ko
-rtl8192ee.ko
-rtl8192se.ko
 r8188eu.ko
 r8192e_pci.ko
 r8192u_usb.ko