cpu: Fix InvalidRegClass access in CheckerCPU

This is fixing long regressions:

https://jenkins.gem5.org/job/nightly/252/console

Change-Id: Ica56b950e5091d3357060f566e02195cc8136924
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60449
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
1 file changed