mem: Fix the respondEvent check in DRAM interface

This change fixes the respondEvent schedule check
in DRAM interface to make sure that the correct respondEvent
is checked for a given pseudo channel.

Change-Id: Ie5edf48db9f6cf2e7ee4cafe7b774441464d77a4
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/61629
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
3 files changed