kbuild: modversions fix

As pointed out by Mikael Pettersson, we didn't generate checksums for
all exporting objects, due to a thinko of mine.

Rules.make

@@ -131,9 +131,9 @@ else
 	genksyms_smp_prefix := 
 endif
 
-$(MODVERDIR)/$(real-objs-y:.o=.ver): modkern_cflags := $(CFLAGS_KERNEL)
-$(MODVERDIR)/$(real-objs-m:.o=.ver): modkern_cflags := $(CFLAGS_MODULE)
-$(MODVERDIR)/$(export-objs:.o=.ver): export_flags   := -D__GENKSYMS__
+$(addprefix $(MODVERDIR)/,$(real-objs-y:.o=.ver)): modkern_cflags := $(CFLAGS_KERNEL)
+$(addprefix $(MODVERDIR)/,$(real-objs-m:.o=.ver)): modkern_cflags := $(CFLAGS_MODULE)
+$(addprefix $(MODVERDIR)/,$(export-objs:.o=.ver)): export_flags   := -D__GENKSYMS__
 
 c_flags = -Wp,-MD,$(depfile) $(CFLAGS) $(NOSTDINC_FLAGS) \
 	  $(modkern_cflags) $(EXTRA_CFLAGS) $(CFLAGS_$(*F).o) \