ixgbe: use ARRAY_SIZE for array sizing calculation on array buf

Use the ARRAY_SIZE macro on array buf to determine size of the array.
Improvement suggested by coccinelle.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c

@@ -949,7 +949,7 @@ static s32 ixgbe_checksum_ptr_x550(struct ixgbe_hw *hw, u16 ptr,
 	u16 length, bufsz, i, start;
 	u16 *local_buffer;
 
-	bufsz = sizeof(buf) / sizeof(buf[0]);
+	bufsz = ARRAY_SIZE(buf);
 
 	/* Read a chunk at the pointer location */
 	if (!buffer) {