KVM: x86/mmu: Merge all handle_changed_pte*() functions

Merge __handle_changed_pte() and handle_changed_spte_acc_track() into a
single function, handle_changed_pte(), as the two are always used
together.  Remove the existing handle_changed_pte(), as it's just a
wrapper that calls __handle_changed_pte() and
handle_changed_spte_acc_track().

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
[sean: massage changelog]
Link: https://lore.kernel.org/r/20230321220021.2119033-14-seanjc@google.com


Signed-off-by: Sean Christopherson <seanjc@google.com>