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_net.c

@@ -18,6 +18,7 @@
 #include <common.h>
 #include <efi_loader.h>
 #include <malloc.h>
+#include <net.h>
 
 static const efi_guid_t efi_net_guid = EFI_SIMPLE_NETWORK_PROTOCOL_GUID;
 static const efi_guid_t efi_pxe_base_code_protocol_guid =