Remove hard-coded subdirectory paths for configs

Previously, the subdirectories in which the sub-json files were searched
in were hardcoded. Now, DRAMSys simply searches in the directory of the
base config, making this approach more flexible.

configs/lpddr4-example.json

@@ -1,14 +1,14 @@
 {
     "simulation": {
-        "addressmapping": "am_lpddr4_8Gbx16_brc.json",
-        "mcconfig": "fr_fcfs.json",
-        "memspec": "JEDEC_8Gb_LPDDR4-3200_16bit.json",
-        "simconfig": "example.json",
+        "addressmapping": "addressmapping/am_lpddr4_8Gbx16_brc.json",
+        "mcconfig": "mcconfig/fr_fcfs.json",
+        "memspec": "memspec/JEDEC_8Gb_LPDDR4-3200_16bit.json",
+        "simconfig": "simconfig/example.json",
         "simulationid": "lpddr4-example",
         "tracesetup": [
             {
                 "clkMhz": 200,
-                "name": "example.stl"
+                "name": "traces/example.stl"
             }
         ]
     }