KVM: SVM: Add manipulation functions for misc intercepts

This patch wraps changes to the misc intercepts of SVM
into seperate functions to abstract nested-svm better and
prepare the implementation of the vmcb-clean-bits feature.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>