staging: ccree: allocate hash bufs inside req ctx

Move to allocating the buffers needed for requests as part of
the request structure instead of malloc'ing each one on it's
own, making for simpler (and more efficient) code.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>