Revert "toi-3.12: remove annoying WARN_ON, it makes no sense for me"

This reverts commit c0b7520022e0aa0663fa0bacb41733ccb1b53bcf.
Merge remote-tracking branch 'tuxonice-kernel/tuxonice-3.12' into toi-3.12
fix for dmesg crash dump from TOI on resume...

Nigel, if there is no TOI hibernation image, currently TOI will produce
a stack trace:

...

There seems to be no big side effects, just the dmesg log...

The problem is in the toi_bio_core code, where it knows to avoid resume
attempt if check for hibernation image returns -1 == no signature,
however still tries when it is 0 == no image found.

Here is a simple patch to fix that logic (also attached to
prevent format mangling):

...

Thanks for your time in this project and wish you more job satisfaction
in the next year

Woody Suwalski
Ottawa
Merge branch 'toi-3.12' into pf-3.12