env: Move get_env_id() to env.h

Move this function over to the new header file. Also rename it to have an
env_ prefix like the other functions.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index ce5a15e..73005ff 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <env.h>
 #include <stdio_dev.h>
 #include <net.h>
 
@@ -55,7 +56,7 @@
 	static struct in_addr netmask;
 	static struct in_addr our_ip;
 	static int env_changed_id;
-	int env_id = get_env_id();
+	int env_id = env_get_id();
 
 	/* update only when the environment has changed */
 	if (env_changed_id != env_id) {
@@ -75,7 +76,7 @@
 {
 	const char *p;
 	static int env_changed_id;
-	int env_id = get_env_id();
+	int env_id = env_get_id();
 
 	/* update only when the environment has changed */
 	if (env_changed_id != env_id) {