add debug register definition in header
Merge pull request #1 from arcbbb/tmp

add debug register definition in header
improve the descriptions of FIFO

Fixes #5
Merge remote-tracking branch 'f9-upstream/master'
ktimer_event_handler: remove dead code
Reduce compiler optimization to avoid runtime crash

gcc -O1 is known to cause Memory fault. At present, we disable
optimizations as workaround.