KVM: x86: Move x2APIC ICR helper above kvm_apic_write_nodecode()

Hoist kvm_x2apic_icr_write() above kvm_apic_write_nodecode() so that a
local helper to _read_ the x2APIC ICR can be added and used in the
nodecode path without needing a forward declaration.

No functional change intended.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240719235107.3023592-3-seanjc@google.com


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