XEN / ACPI: Make XEN ACPI depend on X86

When ACPI is enabled on ARM64, XEN ACPI will also compiled
into the kernel, but XEN ACPI is x86 dependent, so introduce
CONFIG_XEN_ACPI to make it depend on x86 before XEN ACPI is
functional on ARM64.

CC: Julien Grall <julien.grall@linaro.org>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: David Vrabel <david.vrabel@citrix.com>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

drivers/xen/Kconfig

@@ -253,4 +253,8 @@ config XEN_EFI
 	def_bool y
 	depends on X86_64 && EFI
 
+config XEN_ACPI
+	def_bool y
+	depends on X86 && ACPI
+
 endmenu

drivers/xen/Makefile

@@ -13,7 +13,7 @@ CFLAGS_efi.o				+= -fshort-wchar
 
 dom0-$(CONFIG_PCI) += pci.o
 dom0-$(CONFIG_USB_SUPPORT) += dbgp.o
-dom0-$(CONFIG_ACPI) += acpi.o $(xen-pad-y)
+dom0-$(CONFIG_XEN_ACPI) += acpi.o $(xen-pad-y)
 xen-pad-$(CONFIG_X86) += xen-acpi-pad.o
 dom0-$(CONFIG_X86) += pcpu.o
 obj-$(CONFIG_XEN_DOM0)			+= $(dom0-y)