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>

lib/efi_loader/efi_device_path.c

@@ -8,6 +8,7 @@
 #include <common.h>
 #include <blk.h>
 #include <dm.h>
+#include <net.h>
 #include <usb.h>
 #include <mmc.h>
 #include <nvme.h>