Revert "Don't pass any filesystem flags for f2fs"

This reverts commit 3650264e.

We want that as a patch in d/patches/

vmdebootstrap/filesystem.py

@@ -182,7 +182,7 @@ class Filesystem(Base):
     def get_mount_flags(fstype):
         """Return the fstab mount flags for a given file system type."""
         flags = ['errors=remount-ro']
-        if fstype in ['btrfs', 'f2fs']:
+        if fstype == 'btrfs':
             flags = []
 
         return ','.join(flags) or 'defaults'