CI: add qemu_arm64_lwip to the test matrix

Build and run qemu_arm64_lwip_defconfig in CI. This tests the lightweight
IP (lwIP) implementation of the dhcp, tftpboot and ping commands.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d938c7f..d89657e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -27,6 +27,9 @@
     # Clone uboot-test-hooks
     - git config --global --add safe.directory "${CI_PROJECT_DIR}"
     - git clone --depth=1 https://source.denx.de/u-boot/u-boot-test-hooks /tmp/uboot-test-hooks
+    # qemu_arm64_lwip_defconfig is the same as qemu_arm64 but with NET_LWIP enabled.
+    # The test config and the boardenv file from qemu_arm64 can be re-used so create symlinks
+    - ln -s conf.qemu_arm64_na /tmp/uboot-test-hooks/bin/travis-ci/conf.qemu_arm64_lwip_na
     - ln -s travis-ci /tmp/uboot-test-hooks/bin/`hostname`
     - ln -s travis-ci /tmp/uboot-test-hooks/py/`hostname`
     - grub-mkimage --prefix="" -o ~/grub_x86.efi -O i386-efi normal  echo lsefimmap lsefi lsefisystab efinet tftp minicmd
@@ -348,6 +351,12 @@
     TEST_PY_TEST_SPEC: "not sleep"
   <<: *buildman_and_testpy_dfn
 
+qemu_arm64_lwip test.py:
+  variables:
+    TEST_PY_BD: "qemu_arm64_lwip"
+    TEST_PY_TEST_SPEC: "test_net_dhcp or test_net_ping or test_net_tftpboot"
+  <<: *buildman_and_testpy_dfn
+
 qemu_m68k test.py:
   variables:
     TEST_PY_BD: "M5208EVBE"