crypto: omap-sham - make queue length configurable

Crypto driver queue size can now be configured from userspace. This
allows optimizing the queue usage based on use case. Default queue
size is still 10 entries.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>