Move FCH header to a location accessible by all archs

JIRA: https://issues.redhat.com/browse/RHEL-102860

commit b1c26e059536d8acbf9d508374f4b76537e20fb7
Author: Mario Limonciello <mario.limonciello@amd.com>
Date:   Tue Jun 10 15:58:16 2025 -0500

    Move FCH header to a location accessible by all archs

    A new header fch.h was created to store registers used by different AMD
    drivers.  This header was included by i2c-piix4 in
    commit 624b0d5696a8 ("i2c: piix4, x86/platform: Move the SB800 PIIX4 FCH
    definitions to <asm/amd/fch.h>"). To prevent compile failures on non-x86
    archs i2c-piix4 was set to only compile on x86 by commit 7e173eb82ae9717
    ("i2c: piix4: Make CONFIG_I2C_PIIX4 dependent on CONFIG_X86").
    This was not a good decision because loongarch and mips both actually
    support i2c-piix4 and set it enabled in the defconfig.

    Move the header to a location accessible by all architectures.

    Fixes: 624b0d5696a89 ("i2c: piix4, x86/platform: Move the SB800 PIIX4 FCH definitions to <asm/amd/fch.h>")
    Suggested-by: Hans de Goede <hansg@kernel.org>
    Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
    Reviewed-by: Hans de Goede <hansg@kernel.org>
    Link: https://lore.kernel.org/r/20250610205817.3912944-1-superm1@kernel.org
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
    Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Signed-off-by: David Arcari <darcari@redhat.com>

arch/x86/kernel/cpu/amd.c

@@ -9,7 +9,7 @@
 #include <linux/sched/clock.h>
 #include <linux/random.h>
 #include <linux/topology.h>
-#include <asm/amd/fch.h>
+#include <linux/platform_data/x86/amd-fch.h>
 #include <asm/processor.h>
 #include <asm/apic.h>
 #include <asm/cacheinfo.h>

drivers/i2c/busses/i2c-piix4.c

@@ -34,7 +34,7 @@
 #include <linux/dmi.h>
 #include <linux/acpi.h>
 #include <linux/io.h>
-#include <asm/amd/fch.h>
+#include <linux/platform_data/x86/amd-fch.h>
 
 #include "i2c-piix4.h"
 

drivers/platform/x86/amd/pmc/pmc-quirks.c

@@ -11,7 +11,7 @@
 #include <linux/dmi.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
-#include <asm/amd/fch.h>
+#include <linux/platform_data/x86/amd-fch.h>
 
 #include "pmc.h"