cmd: nvedit: Fix typo in 'illegal character' error

Fix a typo: add a space after the single quote in 'illegal character'
error message in 'env set' command

Signed-off-by: Ivan Orlov <ivan.orlov@codethink.co.uk>
diff --git a/env/common.c b/env/common.c
index 656748c..26e5cbe 100644
--- a/env/common.c
+++ b/env/common.c
@@ -85,7 +85,7 @@
 	name = argv[1];
 
 	if (strchr(name, '=')) {
-		printf("## Error: illegal character '='"
+		printf("## Error: illegal character '=' "
 		       "in variable name \"%s\"\n", name);
 		return 1;
 	}