Replace CONFIG_THREAD_OPTIONROMS with a runtime config setting.

Replace the CONFIG_THREAD_OPTIONROMS option with the CBFS (or fw_cfg)
file "etc/threads".  This allows for the "threads during optionrom"
capability to be enabled/disabled without requiring SeaBIOS to be
recompiled.  A value of "2" in this file will enable threads to run
during option rom execution.

This change also allows for all threads to be disabled via the same
runtime config file.  Setting the file to a value of "0" will cause
SeaBIOS to perform all hardware initialization serially.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
acpi: Move acpi parsing logic from acpi.c to biostables.c / paravirt.c.

After this change, src/fw/acpi.c only contains the legacy code for
generating ACPI tables.  This change only contains code movement - no
logic is changed.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
smbios: Move smbios parsing logic from smbios.c to biostables.c.

After this change, src/fw/smbios.c only contains the legacy code for
generating SMBIOS tables.  This change only contains code movement -
no logic is changed.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Move PirAddr definition from pirtable.c to biostables.c.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Use biostables.c for copying bios tables even when generating them.

Use the biostables.c copy_pir(), copy_smbios(), copy_acpi_rsdp(), and
copy_mptable() code even when using the legacy bios table generation
code.  This unifies the final bios table deployment code between qemu,
coreboot, and csm.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Document no new changes to pirtable.c, mptable.c, acpi.c, and smbios.c.

Add a note to the code that generates the pir, mptable, smbios, and
smbios tables that no new changes are expected.  Going forward, it is
expected that if any changes are needed to these bios tables that
SeaBIOS will get the tables passed in from upstream.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
apm: Remove old Bochs mechanism for shutdown/suspend/standby.

Remove the old mechanism that used port 0x8900 to send apm signals.
Recent versions of QEMU no longer support this port.  Bochs and QEMU
only ever supported shutdown anyway, and shutdown is already available
via an ACPI mechanism.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Minor - remove unused includes from pci.c.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>