x86/xen: split off enlighten_pv.c

Basically, enlighten.c is renamed to enlighten_pv.c and some code moved
out to common enlighten.c.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

arch/x86/xen/Makefile

@@ -7,13 +7,13 @@ endif
 
 # Make sure early boot has no stackprotector
 nostackp := $(call cc-option, -fno-stack-protector)
-CFLAGS_enlighten.o		:= $(nostackp)
+CFLAGS_enlighten_pv.o		:= $(nostackp)
 CFLAGS_mmu.o			:= $(nostackp)
 
 obj-y		:= enlighten.o setup.o multicalls.o mmu.o irq.o \
 			time.o xen-asm.o xen-asm_$(BITS).o \
 			grant-table.o suspend.o platform-pci-unplug.o \
-			p2m.o apic.o pmu.o
+			p2m.o apic.o pmu.o enlighten_pv.o
 
 obj-$(CONFIG_XEN_PVHVM)		+= enlighten_hvm.o
 obj-$(CONFIG_XEN_PVH)			+= enlighten_pvh.o