env: add missing newline

Signed-off-by: Philip Molloy <philip@philipmolloy.com>
diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 1ed0f7e..cfada0e 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -1742,7 +1742,7 @@
 
 		if (ENVSIZE(0) != ENVSIZE(1)) {
 			fprintf(stderr,
-				"Redundant environments have unequal size");
+				"Redundant environments have unequal size\n");
 			return -1;
 		}
 	}