We have a function parseRateStr() that parses --inbound and
--outbound arguments to both attach-interface and domiftune.
Now that we have all virTypedParams macros needed for QoS,
lets parse even floor attribute. The extended format for the
arguments looks like this then:
--inbound average[,peak[,burst[,floor]]]
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>