hpicfProviderBridgeType controls bridge mode configuration.
A device can function in one of the 4 modes defined above.
vlanBridge - provider bridge feature disabled mode,
all vlans are cvlans.
svlanBridge - provider bridge mode with only svlans.
providerEdgeBridge - provider bridge mode with cvlans and
svlans and mappings between them.
vlanSvlanBridge - provider bridge mode with independent
cvlans and svlans on the same device.
Changing from one mode to another will empty out the
current configuration information and reboot the device.