openssl: add ocf support

Enable OCF (cryptodev) support for openssl as an option.

This requires a patched kernel to export hardware acceleration for
openssl to use it.
If you lack a patched kernel or support it won't break anything, it will
simply fall back to the default software engine from openssl, you'll
just have a slightly bigger libssl/libcrypto.

Tested with 20100325 release + 20101223 patch from the mailing list.

[Peter: slightly tweaked .mk]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>