KVM: Move kvm_{set,release}_page_{clean,dirty}() helpers up in kvm_main.c

Hoist the kvm_{set,release}_page_{clean,dirty}() APIs further up in
kvm_main.c so that they can be used by the kvm_follow_pfn family of APIs.

No functional change intended.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
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: <20241010182427.1434605-29-seanjc@google.com>