the intention of having two ttys pointing to the same cfe console device was.
Also we were not initializing the output[] array passed in as input to
tty_makedev() so one name of the ttys was garbage.
Fix the code that calls cfe_write() to deal with the case where only a partial
buffer is written out.
cfe_cngetc() needs to return if there is no character available as input.
If we don't do this then the cfe_timeout() function will spin forever
because cfe_cngetc() will only ever return if there is valid input.
Approved by: imp (mentor)