Fix VirtualInterfaceMacAddressException message

Previous the message reflected the default value of
create_unique_mac_address_attempts configuration option.

Changed to a generic message.

Change-Id: I55c5f95cfc7ac4183e08a7880cbbb9670a02cef4
Closes-Bug: #1276312
Merge "Fix VirtualInterfaceMacAddressException message"