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/fpga/zynqpl.c b/drivers/fpga/zynqpl.c
index 21624f7..6370caf 100644
--- a/drivers/fpga/zynqpl.c
+++ b/drivers/fpga/zynqpl.c
@@ -9,6 +9,7 @@
 #include <common.h>
 #include <console.h>
 #include <cpu_func.h>
+#include <asm/cache.h>
 #include <asm/io.h>
 #include <fs.h>
 #include <zynqpl.h>