s390/uv: Retrieve UV secrets sysfs support

s390/uv: Retrieve UV secrets sysfs support

Reflect the updated content in the query information UVC to the sysfs at
/sys/firmware/query

* new UV-query sysfs entry for the maximum number of retrievable
  secrets the UV can store for one secure guest.
* new UV-query sysfs entry for the maximum number of association
  secrets the UV can store for one secure guest.
* max_secrets contains the sum of max association and max retrievable
  secrets.

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Link: https://lore.kernel.org/r/20241024062638.1465970-7-seiden@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>