x86: Stop using and delete the x86 IntDevice class.

x86: Stop using and delete the x86 IntDevice class.

Most of its functionality has been exported already. This change makes
the two classes which were inheriting IntDevice create an IntMasterPort
themselves.

Change-Id: I73d17cd79cf8252b0e26dd2576f552bf9054adf4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20825
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>