ACPI: tables: introduce support for FPDT table

ACPI Firmware Performance Data Table (FPDT) provides information about
firmware performance during system boot, S3 suspend and S3 resume.

Have the kernel parse the FPDT table, and expose the firmware
performance data to userspace as sysfs attributes under
/sys/firmware/acpi/fpdt/.

Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>