acpi: stop parsing AML in the kernel; power management is userspace's

Kernel discovery interpreted the whole DSDT/SSDTs (~0.5 MB -> ~9700 nodes) solely to extract the _S5 sleep type for a kernel-side soft-off — ~1-2s of work on the single-core, pre-scheduler critical path, with nothing to overlap it. The ring-3 acpi service already parses the same blobs and owns S5 end-to-end (reads pm1a_cnt from the FADT, writes SLP_TYP itself; orderly-shutdown tests it). So drop the kernel parse entirely.

- all *static*-table parsing stays (MADT/HPET/FADT/MCFG): CPUs, timers, PCIe, and the power register map are still detected from ACPI, not legacy/compat addresses (timer still calibrates via HPET/PM-timer/CPUID, PIT only as last resort)
- kernel keeps reboot (FADT reset register + legacy fallbacks — no AML); soft-off is userspace-only now
- removed PowerInformation.s5/s3, the kernel AML namespace, aml_stats, amlDeviceCount, and the aml import; power.shutdown/enable/sleepS3 gone
- tests: poweroff case retired (S5 covered by orderly-shutdown); discovery drops its S5/AML checks; acpi-parse self-verifies against a device-count floor since there's no kernel count to match

test/qemu_test.py

@@ -365,7 +365,7 @@ CASES = [
      "smp":    4,
      "timeout": 60,
      "expect": r"acpi-parse: ok",
-     "fail":   r"acpi-parse: mismatch|DANOS-TEST-RESULT: FAIL"},
+     "fail":   r"acpi-parse: too few|DANOS-TEST-RESULT: FAIL"},
     # M20.3: the flip — ps2-bus now comes up from the acpi service's report, not
     # a kernel-built node. Ordered: report -> spawn -> the driver attaches its
     # keyboard, proving discovery runs entirely in ring 3 (docs/discovery.md).
@@ -492,9 +492,8 @@ CASES = [
      "fail":   r"DANOS-TEST-RESULT: FAIL"},
     # The ACPI power path succeeds by QEMU *exiting* (S5 off / reset), so match the
     # pre-transition marker; the FAIL line only appears if the transition didn't take.
-    {"name": "poweroff",
-     "expect": r"DANOS-POWER: attempting poweroff",
-     "fail":   r"DANOS-TEST-RESULT: FAIL"},
+    # Soft-off (S5) is owned by the ring-3 acpi service now (see orderly-shutdown);
+    # the kernel keeps only reboot (FADT reset register, no AML).
     {"name": "reboot",
      "expect": r"DANOS-POWER: attempting reboot",
      "fail":   r"DANOS-TEST-RESULT: FAIL"},