fpga/Makefile: fix ordering rule for power estimator

fpga/Makefile

@@ -136,7 +136,7 @@ $(outdir)/%.sof: $(outdir)/%.mif_update.rpt
 $(outdir)/%.sta.rpt: $(outdir)/%.fit.rpt | $(outdir)/%.sof
 	$(QSTA) $(PROJECT) -c $*
 
-$(outdir)/%.pow.rpt: $(outdir)/%.sta.rpt
+$(outdir)/%.pow.rpt: $(outdir)/%.sta.rpt | $(outdir)/%.sof
 	$(QPOW) $(PROJECT) -c $*
 
 $(foreach rev,$(REVISIONS),$(outdir)/$(rev).%.cof): %.cof.xml $(outdir)