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>

fs/ext4/ext4_common.h

@@ -23,6 +23,7 @@
 #include <ext_common.h>
 #include <ext4fs.h>
 #include <malloc.h>
+#include <asm/cache.h>
 #include <linux/errno.h>
 #if defined(CONFIG_EXT4_WRITE)
 #include "ext4_journal.h"