sparc: Move the microop/macroop base classes out of the ISA desc.

These were just raw C++ classes.

Change-Id: Id2101400d885c6938efb6b94f2949722cfbb94ae
Reviewed-on: https://gem5-review.googlesource.com/5481
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>