icsf: add ASN.1 description for icsf_generate_secret_key

Add the ASN.1 sysntax for the CSFPGSK service used by icsf_generate_secret_key.

Signed-off-by: Marcelo Cerri <mhcerri@linux.vnet.ibm.com>
icsf: add support for mechanisms in icsf_generate_secret_key

Add a new argument in icsf_generate_secret_key that specifies the
mechanism that has to be used. This means that SSL keys are now
supported.

Signed-off-by: Marcelo Cerri <mhcerri@linux.vnet.ibm.com>