configs: Stop disabling SDMA in GPUFS config

Support has been added for SDMA RLC queues which are used for host to
device and device to host "memcpy" calls. Previously the SDMA engine was
disabled which caused GPU BLIT kernels to be called. This removes the
environment variable disabling SDMAs which has two main benefits:

 - It will be much easier to debug host/device transfer by using SDMA
   debug flag.
 - Simulation time is improved since we no longer need detailed GPU
   simulation to copy data and instead are doing a simple large DMA

Change-Id: I7524245731d301b5c26394318f2156ed6b4c983a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/62717
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>

configs/example/gpufs/hip_samples.py

@@ -41,7 +41,6 @@ from ruby import Ruby
 
 samples_runscript = """\
 export LD_LIBRARY_PATH=/opt/rocm/lib:$LD_LIBRARY_PATH
-export HSA_ENABLE_SDMA=0
 export HSA_ENABLE_INTERRUPT=0
 dmesg -n3
 dd if=/root/roms/vega10.rom of=/dev/mem bs=1k seek=768 count=128