KVM: nSVM: Move vmcb_ctrl_area_cached.bus_lock_rip to svm_nested_state

KVM: nSVM: Move vmcb_ctrl_area_cached.bus_lock_rip to svm_nested_state

Move "bus_lock_rip" from "vmcb_ctrl_area_cached" to "svm_nested_state" as
"last_bus_lock_rip" to more accurately reflect what it tracks, and because
it is NOT a cached vmcb12 control field.  The misplaced field isn't all
that apparent in the current code base, as KVM uses "svm->nested.ctl"
broadly, but the bad placement becomes glaringly obvious if
"svm->nested.ctl" is captured as a local "vmcb12_ctrl" variable.

No functional change intended.

Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20260218230958.2877682-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>