test: don't use enum values in ck_assert macros directly

test: don't use enum values in ck_assert macros directly

Unfortunately, typeof(enum something) != typeof(ENUM_VALUE) and produces a
-Wsign-compare warning

Preemptively fix this, it'll show up in the upcoming litest_asssert macros
otherwise.

This fix only applies to helper functions, tests themselves wont (yet) be
switched to the new macros and don't need fixing.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>