Linux SFI __init time API

sfi_init()
called by setup_arch() before IO-APIC setup
find and parse SYST, check-sum, print headers
sfi_platform_init(): parse CPUS, APIC tables

sfi_late_init()
called from start_kernel()
re-map SYST using ioremap()
sfi_acpi_init(): find and parse XSDT