SUNRPC: Remove svc_rqst :: rq_vec

Clean up: This array is no longer used.

On a system with 8-byte pointers and 4KB pages, pahole reports that
the rq_vec[] array accounts for 4144 bytes.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

include/linux/sunrpc/svc.h

@@ -212,7 +212,6 @@ struct svc_rqst {
 	struct page *		*rq_page_end;  /* one past the last page */
 
 	struct folio_batch	rq_fbatch;
-	struct kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
 	struct bio_vec		*rq_bvec;
 
 	__be32			rq_xid;		/* transmission id */