As the ubuntu 16.04 is based on 4.4 kernel, thus we can try to refer the config
file for opnfv config file.

The arch/x86/configs/config-4.4.0-62-generic is the config file used by ubuntu
kernel. Comparing with the opnfv kernel, the key differences are:
 a. Real time config support like NOHZ_FULL, PREMEPMT kernel, different RCU
mechanism,
 b.  Disabling some feature that may impact real time result, like power
management functionality (C/P state). The hotplug support is disabled also
temply now.
 c.  Some ubuntu specific driver is not copied.
 d. Some difference of build-in/module selection, because some config items
are selected automatically and we don't figure out the default value difference
yet. 
 e. Some virtualization support like Xen/HyperV is not enabled yet, to avoid
potential impact.

In future, we should leave only item a/b and remove the differences caused by
item c/d/e.