KVM: x86/mmu: Hoist guest_memfd max level/order helpers "up" in mmu.c

KVM: x86/mmu: Hoist guest_memfd max level/order helpers "up" in mmu.c

Move kvm_max_level_for_order() and kvm_max_private_mapping_level() up in
mmu.c so that they can be used by __kvm_mmu_max_mapping_level().

Opportunistically drop the "inline" from kvm_max_level_for_order().

No functional change intended.

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Message-ID: <20250729225455.670324-14-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>