arch/x86: Declare permanent_smi_handler()

Advertising SMI triggers in FADT is only valid if we exit with
SMI installed. There has been some experiments to delay SMM
installation to OS, yet there are new platforms that allow some
configuration access only to be done inside SMM.

Splitting static HAVE_SMI_HANDLER variable helps to manage cases
where SMM might be both installed and cleared prior to entering
payload.

Change-Id: Iad92c4a180524e15199633693446a087787ad3a2
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
---
M src/include/acpi/acpi.h
M src/mainboard/aopen/dxplplusu/fadt.c
M src/mainboard/emulation/qemu-q35/acpi_tables.c
M src/mainboard/lenovo/t400/fadt.c
M src/mainboard/lenovo/x200/fadt.c
M src/mainboard/roda/rk9/fadt.c
M src/soc/amd/picasso/acpi.c
M src/soc/amd/stoneyridge/acpi.c
M src/soc/intel/baytrail/acpi.c
M src/soc/intel/braswell/acpi.c
M src/soc/intel/broadwell/acpi.c
M src/soc/intel/common/block/acpi/acpi.c
M src/soc/intel/skylake/acpi.c
M src/soc/intel/xeon_sp/cpx/acpi.c
M src/soc/intel/xeon_sp/skx/acpi.c
M src/southbridge/amd/agesa/hudson/fadt.c
M src/southbridge/amd/pi/hudson/fadt.c
M src/southbridge/intel/bd82x6x/lpc.c
M src/southbridge/intel/i82371eb/fadt.c
M src/southbridge/intel/i82801gx/lpc.c
M src/southbridge/intel/i82801ix/i82801ix.c
M src/southbridge/intel/i82801jx/i82801jx.c
M src/southbridge/intel/i82801jx/lpc.c
M src/southbridge/intel/ibexpeak/lpc.c
M src/southbridge/intel/lynxpoint/lpc.c
25 files changed, 37 insertions(+), 30 deletions(-)