Update amd/south_station/fadt.c with various fixes

Update amd/south_station/fadt.c with various fixes

This is a model fadt.c that I would like to use for updating
several other AMD platforms with after acceptance.

- Updated to match ACPI 3.0b specification and added comments
  to reflect that.
- Since smi_cmd is 0, remove commands that rely on it:
  acpi_enable, acpi_disable, & pstate_cnt
  Add comments to that effect.
- Changed preferred_pm_profile to SOHO Server (platform
  specific)
- The southstation platform is legacy free - Updated
  iapc_boot_arch and flags to reflect that.
- Added reset_register flag so that operating systems
  will actually use the reset_reg.  This is important
  on legacy free systems.
- Updated Generic Address Structures to use access_size
  name in the updated acpi.h.  Added access sizes to
  the structures where reasonable.
- Removed 64-bit x_firmware_ctl pointer to facs.  This was
  causing a fwts failure and windows-64 BSOD.
- Added bit width for pm2_cnt_blk and modified gpe0_blk bit
  to match the hardware.

Change-Id: Icf1a982aa122636d1088c8b80f53d04732b54c49
Signed-off-by: Martin L Roth <martin@se-eng.com>
Reviewed-on: http://review.coreboot.org/942
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marcj303@gmail.com>