gpu-compute: Fix off-by-one when creating an AddrRange
gpu-compute: Fix off-by-one when creating an AddrRange

The end value of an AddrRange is already not included in the range,
so subtracting one from the end creates an off-by-one error.

This patch removes the extra -1 that was used when determining the
end of an AddrRange in allocateGpuVma

Change-Id: I75659e9a7fabd991bb37be9aa40f8e409eb21154
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48020
Reviewed-by: Matt Sinclair <d2406197fb1bedd1e23c70c50c510ff0e9ab0f5b@gmail.com>
Reviewed-by: Bobby R. Bruce <b9dba908ffb6c6d8ffe449cc88b3709c13c485c2@ucdavis.edu>
Maintainer: Matt Sinclair <d2406197fb1bedd1e23c70c50c510ff0e9ab0f5b@gmail.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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