env: clean cmd_nvedit.c checkpatch and code style

Cleanup the cmd_nvedit.c checkpatch warnings, errors and coding style.
There are 10 wanrings left about the simple_strtoul() function:
 WARNING: simple_strtoul is obsolete, use kstrtoul instead
 #359: FILE: cmd_nvedit.c:359:
 +		load_addr = simple_strtoul(argv[2], NULL, 16);

 ...

 total: 0 errors, 10 warnings, 1043 lines checked

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
diff --git a/include/environment.h b/include/environment.h
index 951803f..3c8c24b 100644
--- a/include/environment.h
+++ b/include/environment.h
@@ -143,6 +143,9 @@
 # define ENV_HEADER_SIZE	(sizeof(uint32_t))
 #endif
 
+#if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
+extern char *env_name_spec;
+#endif
 
 #define ENV_SIZE (CONFIG_ENV_SIZE - ENV_HEADER_SIZE)