ANDROID: KVM: arm64: Remove __pkvm_host_dirty_log_guest()

Now that dirty logging for no-guests is done from user_mem_abort() with
the standard KVM logic, the __pkvm_host_dirty_log_guest() hypercall is
unused. Remove it.

Bug: 357781595
Bug: 235345873
Change-Id: I573365ec01dbfdf5943670c1128fb2475ce6a107
Signed-off-by: Quentin Perret <qperret@google.com>