vmx_io_bitmap_b should not be allocated twice.

Fixes: 23611332 ("KVM: VMX: refactor setup of global page-sized bitmaps")
Signed-off-by: NJim Mattson <jmattson@google.com>
Reviewed-by: NKrish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>