systemc: Add some error checks to the sc_module constructor.

systemc: Add some error checks to the sc_module constructor.

These match error checks which are already in, for instance, the
sc_port constructor.

Change-Id: I8dfb4ce37bf0e59c6fa879f0afda5112af78b40b
Reviewed-on: https://gem5-review.googlesource.com/c/13290
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>