base: clang-7 can't deduce non type parameter with auto
base: clang-7 can't deduce non type parameter with auto

We now use explicit types instead (size_t)
This is fixing compiler checks, build 224 [1]

[1]: https://jenkins.gem5.org/job/compiler-checks/224/\
    artifact/compile-test-out/clang-version-7/

Change-Id: I5e94652b2fef554b1c47ce2972462401703ca5d5
Signed-off-by: Giacomo Travaglini <8eef13a4f970e2e9372c8d26ad0737b760f99c02@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59430
Reviewed-by: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>
Reviewed-by: Richard Cooper <5451b9f082a6f419264dc2e8898d5200257ca9ce@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Maintainer: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>

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