KVM: s390: Update api documentation for memop ioctl

KVM: s390: Update api documentation for memop ioctl

BugLink: https://bugs.launchpad.net/bugs/1933179
Document all currently existing operations, flags and explain under
which circumstances they are available. Document the recently
introduced absolute operations and the storage key protection flag,
as well as the existing SIDA operations.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20220211182215.2730017-10-scgl@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
(cherry picked from commit 5e35d0eb472b48ac9c8ef7017753b8a1f765aa01 linux-next)
Signed-off-by: Frank Heimes <frank.heimes@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>