rngd_rdrand: Actually perform the correct AES data reduction

rngd_rdrand: Actually perform the correct AES data reduction

The pointers were confused in such a way that the AES data reduction
wasn't actually being performed.  Furthermore, architecturally we need
a 512:1 data reduction, rather than 128:1.  Finally, initialize the IV
to random value during startup and remove some unnecessary buffer
shuffling.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>