configs,gpu-compute: Add configurable LDS bus latency

Previously the LDS bus latency was not configurable in the GPU config
scripts. As a result, the simulations would use the default value from
GPU.py. This commit adds support to change this value as an input
option. The option to use is "--vrf_lm_bus_latency".

Change-Id: I8d8852e6d7b9d03ebec1fe8b392968f396dd3526
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/63652
Maintainer: Matthew Poremba <matthew.poremba@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Matt Sinclair <mattdsinclair.wisc@gmail.com>

configs/example/apu_se.py

@@ -257,6 +257,12 @@ parser.add_argument(
     default=4,
     help="Number of coalescer tokens per CU",
 )
+parser.add_argument(
+    "--vrf_lm_bus_latency",
+    type=int,
+    default=1,
+    help="Latency while accessing shared memory",
+)
 parser.add_argument(
     "--TLB-prefetch", type=int, help="prefetch depth for" "TLBs"
 )
@@ -442,6 +448,7 @@ for i in range(n_cu):
             localMemBarrier=args.LocalMemBarrier,
             countPages=args.countPages,
             max_cu_tokens=args.max_cu_tokens,
+            vrf_lm_bus_latency=args.vrf_lm_bus_latency,
             localDataStore=LdsState(
                 banks=args.numLdsBanks,
                 bankConflictPenalty=args.ldsBankConflictPenalty,