Various fixes and cleanups for x86-64. 

 - Update defconfig
 - Fix some problems in ROM resource scanning (Rene Herman) 
 - Initialize APIC id of CPU 0 (Venkatesh Pallipadi)
 - Always enable swiotlb for GART_IOMMU
 - Fix compilation without IOMMU_GART
 - Remove nodes_present; use standard node_online_map instead.
   This also fixes a bug with no memory on node 0.
 - Switch node<->cpu mapping to arrays. This fixes some awkward
   special cases with no nodes and empty nodes. 
 - Move K8 fallback node setup to common code
 - Eliminate old fake_node.
 - Fix wrong fields in MCE handling (Marc Bevand)
 - Make pci_dma_consistent behave more similar to i386 to fix Alsa