config: Handle NULL simobject parameters in read_config.py.

Change-Id: If0f87e8ee37099be4d0f3567db4fc34f8467e409
Reviewed-on: https://gem5-review.googlesource.com/6943
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
1 file changed