Do not show disk errors if they are expected.

An error shows up during boot if vold disk has different majors.
On some devices this is expected and set in config, so do not
confuse users and skip the error (as it ain't one)
Bonus: Better log for duplicate state. It was useless...

Change-Id: Ibc047729432e2f6746a9439b828d1443951ade1f