x86: Move itss.c from Apollo Lake to a more generic location

The Interrupt Timer Subsystem (ITSS) is not specific to Apollo Lake, so
move it to a common location within arch/x86.

Signed-off-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: conditionally build itss.c]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/apollolake/Makefile b/arch/x86/cpu/apollolake/Makefile
index 1760df5..f99f2c6 100644
--- a/arch/x86/cpu/apollolake/Makefile
+++ b/arch/x86/cpu/apollolake/Makefile
@@ -19,7 +19,6 @@
 endif
 
 obj-y += hostbridge.o
-obj-y += itss.o
 obj-y += lpc.o
 obj-y += p2sb.o
 obj-y += pch.o
diff --git a/arch/x86/cpu/intel_common/Makefile b/arch/x86/cpu/intel_common/Makefile
index cc4e1c9..1e7a72f 100644
--- a/arch/x86/cpu/intel_common/Makefile
+++ b/arch/x86/cpu/intel_common/Makefile
@@ -27,6 +27,9 @@
 endif
 endif
 obj-y += pch.o
+ifdef CONFIG_INTEL_APOLLOLAKE
+obj-y += itss.o
+endif
 
 ifdef CONFIG_SPL
 ifndef CONFIG_SPL_BUILD
diff --git a/arch/x86/cpu/apollolake/itss.c b/arch/x86/cpu/intel_common/itss.c
similarity index 100%
rename from arch/x86/cpu/apollolake/itss.c
rename to arch/x86/cpu/intel_common/itss.c