afs: Locally initialise the contents of a new symlink on creation

afs: Locally initialise the contents of a new symlink on creation

Since we know what the contents of a symlink will be when we create it on
the server, initialise its contents locally too to avoid the need to
download it.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-31-dhowells@redhat.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>