Sets ENOENT when appropriate

Userspace will often require ENOENT be set after syscalls fail in a
certain way.  For instance, cp stats the destination, and if it gets a
generic error, the program aborts.  It ought to get ENOENT (or success).

We'll run into this in any place where userspace makes decisions based
on errno.
Fix mount chan type error
Removes extra print funcs from devcons

Unused, and if they were used, we should probably use our own.