Refactor node validation in FuseDaemon

Refactor validation logic in FuseDaemon to make to more comprehensible.
This is a no-op refactor.

Bug: 179914046
Bug: 176547697

Test: atest CtsScopedStorageDeviceOnlyTest:ScopedStorageDeviceTest
Change-Id: I7964f17f97e52054ad32a4d42b9d31f797816c6a
1 file changed