KVM: SVM: Clean up rip handling in vmrun emulation

This patch changes the rip handling in the vmrun emulation
path from using next_rip to the generic kvm register access
functions.

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