FCH controller clock configuration slightly differs across AMD's
SOC architectures. Newer family of SOC only support a 48MHz fix
clock while stoney SOC family has a clk_mux to choose 48MHz and
25 MHz clk. At present fixed clk support is only enabled for RV
architecture using "is-rv" device property initialized from boot
loader. This limit 48MHz fixed clock gate support to RV platform
unless we add similar device property in boot loader for other
architectures.

Add pci_device_id table with Stoney platform id and replace "is-rv"
device property check with pci id match to add clk mux support with
25MHz and 48MHz clk support based on clk mux selection. This enable
48Mhz fixed fch clock support by default on all newer SOC's except
stoney. Also replace RV with FIXED as a generic naming conventions
across all platforms and changed module description.
Signed-off-by: Ajit Kumar Pandey <AjitKumar.Pandey@amd.com>
Reviewed-by: Mario Limonciello <Mario.Limonciello@amd.com>
Link: https://lore.kernel.org/r/20211212180527.1641362-2-AjitKumar.Pandey@amd.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>