swiotlb: Don't include linux/swiotlb.h twice in lib/swiotlb.c

There's no point in including the linux/swiotlb.h header twice in
lib/swiotlb.c - this patch gets rid of the unneeded include.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

lib/swiotlb.c

@@ -23,7 +23,6 @@
 #include <linux/spinlock.h>
 #include <linux/swiotlb.h>
 #include <linux/string.h>
-#include <linux/swiotlb.h>
 #include <linux/types.h>
 #include <linux/ctype.h>
 #include <linux/highmem.h>