afs: Remove the "autocell" mount option

afs: Remove the "autocell" mount option

Remove the "autocell" mount option.  It was an attempt to do automounting
of arbitrary cells based on what the user looked up but within the root
directory of a mounted volume.  This isn't really the right thing to do,
and using the "dyn" mount option to get the dynamic root is the right way
to do it.  The kafs-client package uses "-o dyn" when mounting /afs, so it
should be safe to drop "-o autocell".

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250224234154.2014840-7-dhowells@redhat.com/
Link: https://lore.kernel.org/r/20250310094206.801057-3-dhowells@redhat.com/