gpu-compute,misc: Removed unused 'vaddr' capture

gpu-compute,misc: Removed unused 'vaddr' capture

Clang compilers return a `error: lambda capture 'vaddr' is not used`
error when compiling HSAIL_X86/gem5.opt. This unused lambda capture has
therefore been removed.

Change-Id: I2a7c58174a9ef83435099ab4daf84c762f017dd4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29533
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>