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/drivers/mtd/nand/raw/mxs_nand.c b/drivers/mtd/nand/raw/mxs_nand.c
index e3516cd..a7852a8 100644
--- a/drivers/mtd/nand/raw/mxs_nand.c
+++ b/drivers/mtd/nand/raw/mxs_nand.c
@@ -16,6 +16,7 @@
 #include <common.h>
 #include <cpu_func.h>
 #include <dm.h>
+#include <asm/cache.h>
 #include <linux/mtd/rawnand.h>
 #include <linux/sizes.h>
 #include <linux/types.h>