mem-cache: Fix destructor of `BasePrefetcher::PrefetchInfo`.

mem-cache: Fix destructor of `BasePrefetcher::PrefetchInfo`.

The destructor of `BasePrefetcher::PrefetchInfo` was calling `delete` for a
dynamically-allocated array. Changed to `delete[]` to remove potential undefined
behaviour.

Change-Id: I6f531bfb6fb7108f1d3e743ae0384d80173e15ef
Signed-off-by: Isaac Sánchez Barrera <isaac.sanchez@bsc.es>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22843
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>