xen: move features.c from arch/x86/xen/features.c to drivers/xen

ia64/xen also uses it too. Move it into common place so that
ia64/xen can share the code.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/xen/Makefile

-obj-y		:= enlighten.o setup.o features.o multicalls.o mmu.o \
+obj-y		:= enlighten.o setup.o multicalls.o mmu.o \
 			events.o time.o manage.o xen-asm.o
 
 obj-$(CONFIG_SMP)	+= smp.o

drivers/xen/Makefile

-obj-y	+= grant-table.o
+obj-y	+= grant-table.o features.o
 obj-y	+= xenbus/