tests/docker: Remove Debian 9 remnant lines

Debian 9 base container has been removed in commits
e3755276 and c9d78b06. Remove the last remnants.

Fixes: e3755276 ("tests/docker: Remove old Debian 9 containers")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-Id: <20210107072933.3828450-1-f4bug@amsat.org>
Message-Id: <20210114165730.31607-2-alex.bennee@linaro.org>

tests/docker/Makefile.include

@@ -108,7 +108,6 @@ ifneq ($(HOST_ARCH),x86_64)
 DOCKER_PARTIAL_IMAGES += debian-mips-cross debian-mipsel-cross debian-mips64el-cross
 DOCKER_PARTIAL_IMAGES += debian-ppc64el-cross
 DOCKER_PARTIAL_IMAGES += debian-s390x-cross
-DOCKER_PARTIAL_IMAGES += debian-win32-cross debian-win64-cross
 DOCKER_PARTIAL_IMAGES += fedora travis
 endif