The struct kvm_sev_launch_measure has a constant and small size, and
therefore we can use a regular local variable for it instead of
allocating and freeing heap memory for it.

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20211011173026.2454294-3-dovmurik@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>