修复cortex-m4硬件浮点出栈错误的问题

mkrtos_user/server/init/src/test/printf_test.c

@@ -7,8 +7,13 @@ void printf_test(void)
     printf("print test2.\n");
     float a = 1.1;
     float b = 1.2;
-    float c = a + b;
-    printf("%c %d %f\n", 'a', 1234, 1.1);
-    c = c;
-    printf("%c %d %lf\n", 'a', 1234, 1.1);
+    float c;
+
+    while (1)
+    {
+        c = a + b;
+        printf("%c %d %f\n", 'a', 1234, 1.1);
+        c = c;
+        printf("%c %d %lf\n", 'a', 1234, 1.1);
+    }
 }