tests/tcg/nios2/Makefile.target has accidentally been added
to the Microblaze section. Move it into the correct nios2
section instead - and while we're at it, it should also cover
the whole folder, and not only the Makefile.

Fixes: 67f80eb4 ("tests/tcg: enable debian-nios2-cross for test building")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230119130326.2030297-1-thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230124180127.1881110-19-alex.bennee@linaro.org>