nfs: do not catch ChimeraFsExceptions

vfs layer must convert all ChimeraFsExceptions to corresponding
NfsExceptions.

Remove 'catch all io exception' block to to handle them as bugs.

Acked-by: Karsten Schwank
Target: master
basic-server: update h2 db to 1.4.178

Acked-by: Gerd Behrmann