configs: enable UNIT_TEST on qemu_arm_defconfig

The lib_test_uuid_to_le test fails on 32-bit systems. But we never caught
this in our CI because we never ran any of our C unit tests on 32-bit.

Enable CONFIG_UNIT_TEST on qemu_arm_defconfig.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/qemu_arm_defconfig b/configs/qemu_arm_defconfig
index d042aea..cc4f454 100644
--- a/configs/qemu_arm_defconfig
+++ b/configs/qemu_arm_defconfig
@@ -67,3 +67,4 @@
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_EHCI_PCI=y
 CONFIG_TPM=y
+CONFIG_UNIT_TEST=y