virtio_console: Mark 2 tests only for virtserialport

virtconsole uses virtserialport and creates console on top of it.
It creates an additional layer between the port and the user
and as the result it handles certain things differently, like
Non-blocking mode and not-connected-host are situations, which are
not handled and there is currently no plan of when and how it will
be handled as console is always connected to virtserialport and
console always uses blocking mode to talk to virtserialport.
That's why it doesn't make sense to run tests and pretend it
should act as virtserialport.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>