KVM: PPC: e500: Use __kvm_faultin_pfn() to handle page faults

[ Upstream commit 419cfb98 ]

Convert PPC e500 to use __kvm_faultin_pfn()+kvm_release_faultin_page(),
and continue the inexorable march towards the demise of
kvm_pfn_to_refcounted_page().

Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-55-seanjc@google.com>
Stable-dep-of: 87ecfdbc ("KVM: e500: always restore irqs")
Signed-off-by: Sasha Levin <sashal@kernel.org>