net: dc2114x: Include env.h to permit reading the environment

This file uses the environment but does not include the header file.
Update it.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/net/dc2114x.c

@@ -3,6 +3,7 @@
 #include <asm/io.h>
 #include <cpu_func.h>
 #include <dm.h>
+#include <env.h>
 #include <malloc.h>
 #include <net.h>
 #include <netdev.h>