KVM: SVM: let init_vmcb() take struct vcpu_svm as parameter

Change the parameter of the init_vmcb() function in the kvm-amd module from
struct vmcb to struct vcpu_svm.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Markus Rechberger <markus.rechberger@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>