ACPI: APD: Add a fmw property is_raven

Since there is slight difference in AMD RV based soc in misc
clk architecture. The fmw property will help in differentiating
the SoCs.

Signed-off-by: Akshu Agrawal <akshu.agrawal@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>