swiotlb: tidy up includes

SWIOTLB's includes have become a great big mess. Restore some order by
consolidating the random different blocks, sorting alphabetically, and
purging some clearly unnecessary entries - linux/io.h is now included
unconditionally, so need not be duplicated in the restricted DMA pool
case; similarly, linux/io.h subsumes asm/io.h; and by now it's a
mystery why asm/dma.h was ever here at all.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/swiotlb.c

@@ -21,38 +21,33 @@
 #define pr_fmt(fmt) "software IO TLB: " fmt
 
 #include <linux/cache.h>
+#include <linux/cc_platform.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
 #include <linux/dma-direct.h>
 #include <linux/dma-map-ops.h>
-#include <linux/mm.h>
 #include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/io.h>
+#include <linux/iommu-helper.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/scatterlist.h>
+#include <linux/set_memory.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/swiotlb.h>
-#include <linux/pfn.h>
 #include <linux/types.h>
-#include <linux/ctype.h>
-#include <linux/highmem.h>
-#include <linux/gfp.h>
-#include <linux/scatterlist.h>
-#include <linux/cc_platform.h>
-#include <linux/set_memory.h>
-#include <linux/debugfs.h>
 #ifdef CONFIG_DMA_RESTRICTED_POOL
-#include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/slab.h>
 #endif
 
-#include <asm/io.h>
-#include <asm/dma.h>
-
-#include <linux/io.h>
-#include <linux/init.h>
-#include <linux/memblock.h>
-#include <linux/iommu-helper.h>
-
 #define CREATE_TRACE_POINTS
 #include <trace/events/swiotlb.h>