Generic KVM stats are those collected in architecture independent code
or those supported by all architectures; put all generic statistics in
a separate structure.  This ensures that they are defined the same way
in the statistics API which is being added, removing duplication among
different architectures in the declaration of the descriptors.

No functional change intended.
Reviewed-by: NDavid Matlack <dmatlack@google.com>
Reviewed-by: NRicardo Koller <ricarkol@google.com>
Reviewed-by: NKrish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: NJing Zhang <jingzhangos@google.com>
Message-Id: <20210618222709.1858088-2-jingzhangos@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>