Blackfin: push down asm/ includes and out of bfin-global.h

Avoid including unnecessary headers all the time as well as circular
includes with core requirements.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/dma-mapping.c

@@ -17,6 +17,7 @@
 #include <linux/scatterlist.h>
 #include <asm/cacheflush.h>
 #include <asm/bfin-global.h>
+#include <asm/sections.h>
 
 static spinlock_t dma_page_lock;
 static unsigned long *dma_page;