rhel: remove openvswitch-kmod package from build, rhel6

rhel: remove openvswitch-kmod package from build, rhel6

This patch only affects rhel6 spec file.

Previouly the kernel_module_package macro is used to generate spec file
template to build kmod-openvswitch RPM. The main package only contains
the openvswitch.conf for depmod. The macro is now removed. Everything is
built in the main package instead. This effectively removes the redudant
openvswitch-kmod package from the build.

Signed-off-by: Martin Xu <martinxu9.ovs@gmail.com>
CC: Greg Rose <gvrose8192@gmail.com>
CC: Ben Pfaff <blp@ovn.org>
CC: Flavio Leitner <fbl@redhat.com>
CC: Aaron Conole <aconole@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>