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>

arch/mips/include/asm/cacheops.h

@@ -8,6 +8,8 @@
 #ifndef	__ASM_CACHEOPS_H
 #define	__ASM_CACHEOPS_H
 
+#include <asm/cache.h>
+
 #ifndef __ASSEMBLY__
 
 static inline void mips_cache(int op, const volatile void *addr)