xen: arm: enable balloon driver

The code is now in a state where can just enable it.

Drop the *_xenballloned_pages duplicates since these are now supplied
by the balloon code.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/Makefile

@@ -1,8 +1,8 @@
 ifneq ($(CONFIG_ARM),y)
-obj-y	+= manage.o balloon.o
+obj-y	+= manage.o
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 endif
-obj-y	+= grant-table.o features.o events.o
+obj-y	+= grant-table.o features.o events.o balloon.o
 obj-y	+= xenbus/
 
 nostackp := $(call cc-option, -fno-stack-protector)