gpu-compute: Number of TLBs equal to number of CUs

gpu-compute: Number of TLBs equal to number of CUs

The n_cu variable in GPUTLBConifig.py did not take
the number of CUs into consideration and instead
calculated the number of TLBs using cu_per_sa,
sa_per_complex, num_gpu_complexes. Thus changing
the number of cus (n_cus) and none of the other flags
resulted in a  segmentation fault since the required
TLBs were not being instantiated

Change-Id: I569a4e6dc7db9b7a81aeede5ac68aacc0f400a5e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32035
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Alexandru Duțu <alexandru.dutu@amd.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>