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>

drivers/bootcount/bootcount.c

@@ -6,6 +6,7 @@
 
 #include <bootcount.h>
 #include <cpu_func.h>
+#include <asm/cache.h>
 #include <linux/compiler.h>
 
 #if !defined(CONFIG_DM_BOOTCOUNT)

drivers/bootcount/bootcount_ram.c

@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <cpu_func.h>
+#include <asm/cache.h>
 #include <asm/io.h>
 
 DECLARE_GLOBAL_DATA_PTR;