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>

common/board_f.c

@@ -40,6 +40,7 @@
 #include <trace.h>
 #include <video.h>
 #include <watchdog.h>
+#include <asm/cache.h>
 #ifdef CONFIG_MACH_TYPE
 #include <asm/mach-types.h>
 #endif