Yeah! I got the solution
Well, this been a long ago that I've solved the problem. But I forgot to post the solution here, sorry.
First of all, it's not the /proc interface anymore that you are supposed to talk to, it's the /sys interface now. /proc interfaces are now, deprecated.
Boot normally into your system, and then, get into /sys (needs root provilege), and look for the same file name under it. Sorry, but my current system is not having Suspend2, that's why I'm telling you to look for it.
But it should be like: /sys/suspend2/do_resume.
Now, edit your initrd again, and replace the /proc/.../do_resume with the right one from /sys interface. But this time, modify the echoed value to 1. That means:
echo 1 > /sys/suspend2/do_resume
# Deprecated: echo > /proc/suspend2/do_resume
Now, you have a system which can Suspend2 normally, as the earlier Kernels.
Hope that helps.