ACPI: CPPC: Add definition for undefined FADT preferred PM profile value

In the event a new preferred PM profile value is introduced it's best for
code to be able to defensively guard against it so that the wrong settings
don't get applied on a new system that uses this profile but ancient
kernels.
Acked-by: Huang Rui <ray.huang@amd.com>
Suggested-by: Gautham Ranjal Shenoy <gautham.shenoy@amd.com>
Link: https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html#fixed-acpi-description-table-fadtSigned-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Perry Yuan <Perry.Yuan@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/acpi/actbl.h

@@ -307,7 +307,8 @@ enum acpi_preferred_pm_profiles {
 	PM_SOHO_SERVER = 5,
 	PM_APPLIANCE_PC = 6,
 	PM_PERFORMANCE_SERVER = 7,
-	PM_TABLET = 8
+	PM_TABLET = 8,
+	NR_PM_PROFILES = 9
 };
 
 /* Values for sleep_status and sleep_control registers (V5+ FADT) */