fsmgr: revert multiple fs-types/mountpoint (fix N5 boot)

This is apparently breaking N5, so reverting for now.

This reverts commit a794f86522f9125f2547c94ebc7c74d1e7ace013.

Bug: 15709256
Change-Id: I37a5160eead17e153e2c83fa94632ffa5d8553c2
3 files changed