systemc: Start using the m5.systemc module in the test config.py.
systemc: Start using the m5.systemc module in the test config.py.

Start using sc_main and sc_main_result from the systemc module, and
stop using the versions of those functions which are attached to the
SystemC_Kernel SimObject.

Change-Id: I802898038c80ed36e6a9176211cffb7e0fde2d7e
Reviewed-on: https://gem5-review.googlesource.com/c/16564
Maintainer: Gabe Black <5c8aa1266c03186393d9e7b3b4e3b14239af8201@google.com>
Reviewed-by: Andreas Sandberg <c9f5686ee5bd561c93f9de79681eee75bfa7f36e@arm.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5