KVM: x86: Make kvm_lapic_reg_{read,write}() static

Make the low level read/write lapic helpers static, any accesses to the
local APIC from vendor code or non-APIC code should be routed through
proper helpers.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220204214205.3306634-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>