Remove src/nodeinfo

Remove src/nodeinfo

There is no "node driver" as there was before, drivers have to do
their own ACL checking anyway, so they all specify their functions and
nodeinfo is basically just extending conf/capablities.  Hence moving
the code to src/conf/ is the right way to go.

Also that way we can de-duplicate some code that is in virsysfs and/or
virhostcpu that got duplicated during the virhostcpu.c split.  And
Some cleanup is done throughout the changes, like adding the vir*
prefix etc.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>