ifpps: show kernel version and machine type

Lets make the headline output a bit more useful and show the current
kernel version and well as the machine/hardware type.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
ifpps: show machine type only if not in already release name

In Fedora or RHEL/CentOS releases the machine type is already part
of the package name, so show it only, if it does not appear there.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
ifpps: warn about increase -t when high speed

Collecting device statistics on high speed every second can be very
costly, so warn about this in ncurses mode.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>