vswitch.xml: Fix the name of rstp-path-cost option.
For some reason it is documented as 'rstp-port-path-cost', while
the code and some other bits of documentation use 'rstp-path-cost'.
Fixes: ("Rapid Spanning Tree Protocol (IEEE 802.1D).")
lowest port-id is elected as the root.
</column>
- <column name="other_config" key="rstp-port-path-cost"
+ <column name="other_config" key="rstp-path-cost"
type='{"type": "integer"}'>
The port path cost. The Port's contribution, when it is
the Root Port, to the Root Path Cost for the Bridge. By default the
