acpi: Use console for AcpiOsPrintf()

Switch to console::write_ll() in AcpiOsPrintf() and AcpiOsvPrintf() to
make ACPI boot-time output readable:

  [penberg@localhost osv]$ ./scripts/run.py
  ACPI: RSDP 0xfd8d0 00014 (v00 BOCHS )
  ACPI: RSDT 0x3fffe380 00034 (v01 BOCHS  BXPCRSDT 00000001 BXPC 00000001)
  ACPI: FACP 0x3fffff80 00074 (v01 BOCHS  BXPCFACP 00000001 BXPC 00000001)
  ACPI: DSDT 0x3fffe3c0 011A9 (v01   BXPC   BXDSDT 00000001 INTL 20100528)
  ACPI: FACS 0x3fffff40 00040
  ACPI: SSDT 0x3ffff6e0 00858 (v01 BOCHS  BXPCSSDT 00000001 BXPC 00000001)
  ACPI: APIC 0x3ffff5b0 00090 (v01 BOCHS  BXPCAPIC 00000001 BXPC 00000001)
  ACPI: HPET 0x3ffff570 00038 (v01 BOCHS  BXPCHPET 00000001 BXPC 00000001)
  acpi 0 apic 0
  acpi 1 apic 1
  acpi 2 apic 2
  acpi 3 apic 3
  APIC base fee00000
  OSv v0.02-64-ga556eab Copyright 2013 Cloudius Systems
  locale works
  ACPI: RSDP 0xfd8d0 00014 (v00 BOCHS )
  ACPI: RSDT 0x3fffe380 00034 (v01 BOCHS  BXPCRSDT 00000001 BXPC 00000001)
  ACPI: FACP 0x3fffff80 00074 (v01 BOCHS  BXPCFACP 00000001 BXPC 00000001)
  ACPI: DSDT 0x3fffe3c0 011A9 (v01   BXPC   BXDSDT 00000001 INTL 20100528)
  ACPI: FACS 0x3fffff40 00040
  ACPI: SSDT 0x3ffff6e0 00858 (v01 BOCHS  BXPCSSDT 00000001 BXPC 00000001)
  ACPI: APIC 0x3ffff5b0 00090 (v01 BOCHS  BXPCAPIC 00000001 BXPC 00000001)
  ACPI: HPET 0x3ffff570 00038 (v01 BOCHS  BXPCHPET 00000001 BXPC 00000001)
  ACPI: All ACPI Tables successfully acquired

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>