debian: install openvswitch kernel module under "updates" directory

debian: install openvswitch kernel module under "updates" directory

This patch fixes a bug where "modprobe openvswitch" command on Ubuntu
distribution would have sometimes tried to load OVS kernel module that
shipped together with Linux Kernel, even though one had also installed
OVS datapath debian package created with module-assistant.  Because of
this issue force-reload-kmod command occasionally malfunctioned and
failed to load the right kernel module.

This bug happened *occasionally* because the default Ubuntu depmod
configuration in /etc/depmod.d/ubuntu.conf is set to look for kernel
modules first in "updates" directory, then in "ubuntu" directory and
then in other directories.  If there were two openvswitch.ko modules
in "other directories", then modprobe would have loaded kernel
module that was nondeterministically listed first by file system.

Signed-off-by: Ansis Atteka <aatteka@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>