Useless TIOCSERGSTRUCT logic in most serial drivers is not compiled unless CONFIG_DEBUG and CONFIG_SERIAL_TIOCSERGSTRUCT are defined

Various Kconfig files still have references to CONFIG_ variables.  Some in harmless comments, some in config definionts which is not harmless.  All removed

Fix major misthink in Cortex-M0 port:  The Cortex-M0 has no BASEPRI register.  We have to revert to using the nasty PRIMASK register

Fixes to the LM4F clock configuration.  Errors in register handling caused everything to run at half speed