systemc: Stop passing arguments to sc_main.

systemc: Stop passing arguments to sc_main.

These arguments were originally just to make sure arguments could be
successfully passed to sc_main, but serve no intrinsic purpose. There
are some tests which can accept command line arguments to customize
how they run, and having nonsense arguments confuses them and makes
them behave incorrectly.

Change-Id: Ib328edb12e01a97dca778bbf45b10e91dd8c07a6
Reviewed-on: https://gem5-review.googlesource.com/c/13317
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>