The kernel crypto framework sometimes returned an error, sometimes

The kernel crypto framework sometimes returned an error, sometimes
the callback was called, and sometimes both.  So the caller of that
API could not release resources correctly.
A bunch of errors can or should not happen, replace them with an
assert.  Remove redundant checks.  crypto_invoke() should not return
the error, but pass it via callback.
Some old hardware drivers keep part of their inconsistency as I
cannot test them.
OK mpi@