splice: use bvec_set_page to initialize a bvec

Use the bvec_set_page helper to initialize a bvec.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230203150634.3199647-18-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/splice.c

@@ -675,9 +675,8 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 				goto done;
 			}
 
-			array[n].bv_page = buf->page;
-			array[n].bv_len = this_len;
-			array[n].bv_offset = buf->offset;
+			bvec_set_page(&array[n], buf->page, this_len,
+				      buf->offset);
 			left -= this_len;
 			n++;
 		}