ACPI: x86: Introduce a Makefile

There will be more modules coming here, so, introduce a separate
Makefile and include it in parent one via obj-$(CONFIG_X86).
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/Makefile

@@ -56,9 +56,6 @@ acpi-y				+= evged.o
 acpi-y				+= sysfs.o
 acpi-y				+= property.o
 acpi-$(CONFIG_X86)		+= acpi_cmos_rtc.o
-acpi-$(CONFIG_X86)		+= x86/apple.o
-acpi-$(CONFIG_X86)		+= x86/utils.o
-acpi-$(CONFIG_X86)		+= x86/s2idle.o
 acpi-$(CONFIG_DEBUG_FS)		+= debugfs.o
 acpi-y				+= acpi_lpat.o
 acpi-$(CONFIG_ACPI_FPDT)	+= acpi_fpdt.o
@@ -132,3 +129,4 @@ obj-$(CONFIG_ARM64)		+= arm64/
 obj-$(CONFIG_ACPI_VIOT)		+= viot.o
 
 obj-$(CONFIG_RISCV)		+= riscv/
+obj-$(CONFIG_X86)		+= x86/

drivers/acpi/x86/Makefile

+obj-$(CONFIG_ACPI)	+= acpi-x86.o
+acpi-x86-y		+= apple.o
+acpi-x86-y		+= s2idle.o
+acpi-x86-y		+= utils.o