[UBI][HMAC] - Development commit (bug fix progress)

The UBI-HMAC layer is now able to attach a device.
The volume creation still ends up in a Kernel Oops that
seems to occur in another thread (wl-threads perhaps ?)
The Oops was not registered in the syslog ...

Incoming :
-> Work to fix the Oops ...

Along :
-> Tests on the interval trees implementation ?