cifs: Switch crypto buffer to use a folio_queue rather than an xarray

Switch cifs from using an xarray to hold the transport crypto buffer to
using a folio_queue and use ITER_FOLIOQ rather than ITER_XARRAY.

This is part of the process of phasing out ITER_XARRAY.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Tom Talpey <tom@talpey.com>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: linux-cifs@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-25-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/smb/client/cifsglob.h

@@ -255,7 +255,7 @@ struct smb_rqst {
 	struct kvec	*rq_iov;	/* array of kvecs */
 	unsigned int	rq_nvec;	/* number of kvecs in array */
 	struct iov_iter	rq_iter;	/* Data iterator */
-	struct xarray	rq_buffer;	/* Page buffer for encryption */
+	struct folio_queue *rq_buffer;	/* Buffer for encryption */
 };
 
 struct mid_q_entry;