xsk: Remove internal DMA headers

Christoph Hellwig correctly pointed out [1] that the AF_XDP core was
pointlessly including internal headers. Let us remove those includes.

  [1] https://lore.kernel.org/bpf/[email protected]/

Fixes: 1c1efc2 ("xsk: Create and free buffer pool independently from umem")
Reported-by: Christoph Hellwig <[email protected]>
Signed-off-by: Björn Töpel <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: Björn Töpel

net/xdp/xsk_buff_pool.c

@@ -3,9 +3,6 @@
 #include <net/xsk_buff_pool.h>
 #include <net/xdp_sock.h>
 #include <net/xdp_sock_drv.h>
-#include <linux/dma-direct.h>
-#include <linux/dma-noncoherent.h>
-#include <linux/swiotlb.h>
 
 #include "xsk_queue.h"
 #include "xdp_umem.h"