dev,arm: Use the ArmSystem::PageBytes constant in the generic timer.

This component very specific to ARM, and so there's no reason to use
generic interfaces to get the page size.

Change-Id: Id757b5742c807c5f616a6dc8df94a7709932d071
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34171
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed