hw/cpu: core.c can be compiled as common object

There does not seem to be any target specific code in core.c, so we can
put it into "common-obj" instead of "obj" to compile it only once for
all targets.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Reviewed-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/cpu/Makefile.objs

@@ -2,5 +2,4 @@ obj-$(CONFIG_ARM11MPCORE) += arm11mpcore.o
 obj-$(CONFIG_REALVIEW) += realview_mpcore.o
 obj-$(CONFIG_A9MPCORE) += a9mpcore.o
 obj-$(CONFIG_A15MPCORE) += a15mpcore.o
-obj-y += core.o
-
+common-obj-y += core.o