sstatesig: Fix hash equivlanency locked signature issues

sstatesig: Fix hash equivlanency locked signature issues

Using locked signatures with the hash equivalency server ran into
problems. We need to:

a) Ensure the lockedhashes data object is passed from the core to
   any individual tasks using the get/set_taskdata methods

b) Return a locked singature instead of a unihash

c) Write the unihash being used to locked signature lists rather than
   the calculated taskhash

d) Skip warnings of hash mismatch if the hash is a unihash

These changes fix esdk builds (which use locked sigs) when a hash equivalence
server is in use.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>