Mike Fleetwood authored Aug 20, 2016 and Curtis Gedak committed Sep 14, 2016

The comment became completely unnecessary with the transfer of
mount_info and fstab_info into separate Mount_Info module by commit:
    63ec73df
    Split mount_info and fstab_info maps into separate Mount_Info module

It was never necessary to clear one of the mappings at the end of the
device refresh because it was reloaded at the start of the next device
refresh anyway and it is only a small amount of memory.