hw/mips: Mark the "mipssim" machine as deprecated

hw/mips: Mark the "mipssim" machine as deprecated

We are not aware of anybody still using this machine, support for it
has been withdrawn from the Linux kernel (i.e. there also won't be
any future development anymore), and we are not aware of any binaries
online that could be used for regression testing to avoid that the
machine bitrots ... thus let's mark it as deprecated now.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250121103655.1285596-1-thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>