As the comment block in include/trace/define_trace.h says,
TRACE_INCLUDE_PATH should be a relative path to the define_trace.h
../../drivers/lightnvm is the correct relative path.
../../../drivers/lightnvm is working by coincidence because the top
Makefile adds -I$(srctree)/arch/$(SRCARCH)/include as a header
search path, but we should not rely on it.