lib/simbricks/mem: fix makefile to actually build libmem

lib/simbricks/mem/rules.mk

-# Copyright 2021 Max Planck Institute for Software Systems, and
+# Copyright 2022 Max Planck Institute for Software Systems, and
 # National University of Singapore
 #
 # Permission is hereby granted, free of charge, to any person obtaining
@@ -22,13 +22,13 @@
 
 include mk/subdir_pre.mk
 
-lib_pcie := $(d)libpcie.a
+lib_mem := $(d)libmem.a
 
 OBJS := $(addprefix $(d),if.o)
 
 libsimbricks_objs += $(OBJS)
 
-$(lib_pcie): $(OBJS)
+$(lib_mem): $(OBJS)
 
-CLEAN := $(lib_pcie) $(OBJS)
+CLEAN := $(lib_mem) $(OBJS)
 include mk/subdir_post.mk