common: Drop net.h from common header

Move this header out of the common header. Network support is used in
quite a few places but it still does not warrant blanket inclusion.

Note that this net.h header itself has quite a lot in it. It could be
split into the driver-mode support, functions, structures, checksumming,
etc.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/include/asm/mach-imx/dma.h b/arch/arm/include/asm/mach-imx/dma.h
index 247a91a..55eb84c 100644
--- a/arch/arm/include/asm/mach-imx/dma.h
+++ b/arch/arm/include/asm/mach-imx/dma.h
@@ -13,6 +13,7 @@
 #ifndef __DMA_H__
 #define __DMA_H__
 
+#include <asm/cache.h>
 #include <linux/list.h>
 #include <linux/compiler.h>