python: Remove python/embedded.cc's dependence on the rest of gem5.
python: Remove python/embedded.cc's dependence on the rest of gem5.

If embedded python modules are going to be built into other binaries,
then they can't depend on other parts of gem5.

Change-Id: I4e12f1962cb6330e70866a40388689102c23693a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/49420
Maintainer: Gabe Black <d3e8afea784ab4a50a2dbf9149d2eaa8478e1cbc@gmail.com>
Reviewed-by: Andreas Sandberg <c9f5686ee5bd561c93f9de79681eee75bfa7f36e@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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