[arm] fix stm1 encoding, impl bugs
[arm] fix stm1 encoding, impl bugs

moreati/pydgin,moreati/pydgin,futurecore/pydgin,futurecore/pydgin,moreati/pydgin,cornell-brg/pydgin,cornell-brg/pydgin,cornell-brg/pydgin,moreati/pydgin,futurecore/pydgin,cornell-brg/pydgin,futurecore/pydgin