afs: use kvfree() to free memory allocated by kvcalloc()

afs: use kvfree() to free memory allocated by kvcalloc()

op->more_files is allocated with kvcalloc() but released via
afs_put_operation(), which uses kfree() internally. This mismach prevents
the resource from being released properly and may lead to undefined
behavior.

Fix this by using kvfree() to free op->more_files to match its allocation
method.

Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260622090856.2746629-8-dhowells@redhat.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>