i40e: add required include

On some architectures, this header must be explicitly included.

Change-ID: I4bc2eb0531956a7b676489f79d347d55cfe12421
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e.h

@@ -97,10 +97,6 @@
 #define STRINGIFY(foo)  #foo
 #define XSTRINGIFY(bar) STRINGIFY(bar)
 
-#ifndef ARCH_HAS_PREFETCH
-#define prefetch(X)
-#endif
-
 #define I40E_RX_DESC(R, i)			\
 	((ring_is_16byte_desc_enabled(R))	\
 		? (union i40e_32byte_rx_desc *)	\

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -24,6 +24,7 @@
  *
  ******************************************************************************/
 
+#include <linux/prefetch.h>
 #include "i40e.h"
 #include "i40e_prototype.h"