Implement failover for ubsec. Submitted by Subramanian Ramamoorthy

<sram@broadcom.com> with the following comment:

[...] We have implemented failover (ie, if for some reason that the
hardware fails, the implementation detects this failure and performs
this operation as if no hardware is present, ie, in software) for
sometime now and have tested it here with our hardware. [...]

This change was cc:ed to exports@crypto.com