Consolidate the APIC base RESET logic, which is currently spread out
across both x86 and vendor code.  For an in-kernel APIC, the vendor code
is redundant.  But for a userspace APIC, KVM relies on the vendor code
to initialize vcpu->arch.apic_base.  Hoist the vcpu->arch.apic_base
initialization above the !apic check so that it applies to both flavors
of APIC emulation, and delete the vendor code.
Reviewed-by: NReiji Watanabe <reijiw@google.com>
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-19-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>