nvme_manage: handle fgets() failure

fgets() will return NULL if it encounters EOF.

Change-Id: I35b1744514f2a90d6e95156c3916a18c1a4ecce2
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>

examples/nvme/nvme_manage/nvme_manage.c

@@ -240,6 +240,9 @@ get_controller(void)
 
 	while ((ch = getchar()) != '\n' && ch != EOF);
 	p = fgets(address, 64, stdin);
+	if (p == NULL) {
+		return NULL;
+	}
 
 	while (isspace(*p)) {
 		p++;