rhel: Add depmod.d conf file for rhel6 kmod package.

It looks like for Centos6.4, there is an upstream openvswitch
kernel module already installed. When we try to install kmod-openvswitch
package from this tree's pre-1.10 branches, we get the following warning:
"brcompat.ko needs unknown symbol ovs_dp_ioctl_hook".

Also, after installing the kmod-openvswitch package, if we run
"modprobe openvswitch", the upstream kernel module gets loaded.
We should instead load the kernel module compiled from this tree.

This patch fixes both the above issues.

Bug #15829.
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>