docs: kvm: fix referenced ioctl symbol

The actual symbol that is exported and usable is
'KVM_MEMORY_ENCRYPT_OP', not 'KVM_MEM_ENCRYPT_OP'

$ git grep -l KVM_MEM_ENCRYPT_OP
Documentation/virt/kvm/amd-memory-encryption.rst

$ git grep -l KVM_MEMORY_ENCRYPT_OP
Documentation/virt/kvm/api.rst
arch/x86/kvm/x86.c
include/uapi/linux/kvm.h
tools/include/uapi/linux/kvm.h

While we're in there, update the KVM API category for
KVM_MEMORY_ENCRYPT_OP. It is called on a VM file descriptor.
Signed-off-by: Connor Kuehl <ckuehl@redhat.com>
Link: https://lore.kernel.org/r/20200819211952.251984-1-ckuehl@redhat.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/virt/kvm/amd-memory-encryption.rst

@@ -53,11 +53,11 @@ key management interface to perform common hypervisor activities such as
 encrypting bootstrap code, snapshot, migrating and debugging the guest. For more
 information, see the SEV Key Management spec [api-spec]_
 
-The main ioctl to access SEV is KVM_MEM_ENCRYPT_OP.  If the argument
-to KVM_MEM_ENCRYPT_OP is NULL, the ioctl returns 0 if SEV is enabled
+The main ioctl to access SEV is KVM_MEMORY_ENCRYPT_OP.  If the argument
+to KVM_MEMORY_ENCRYPT_OP is NULL, the ioctl returns 0 if SEV is enabled
 and ``ENOTTY` if it is disabled (on some older versions of Linux,
 the ioctl runs normally even with a NULL argument, and therefore will
-likely return ``EFAULT``).  If non-NULL, the argument to KVM_MEM_ENCRYPT_OP
+likely return ``EFAULT``).  If non-NULL, the argument to KVM_MEMORY_ENCRYPT_OP
 must be a struct kvm_sev_cmd::
 
        struct kvm_sev_cmd {

Documentation/virt/kvm/api.rst

@@ -4211,7 +4211,7 @@ H_GET_CPU_CHARACTERISTICS hypercall.
 
 :Capability: basic
 :Architectures: x86
-:Type: system
+:Type: vm
 :Parameters: an opaque platform specific structure (in/out)
 :Returns: 0 on success; -1 on error