pios: convert all pios files to use unix EOL (LF-only) line ends

Whitespace only.  No functional changes.
````
for i in flight/PiOS/inc \
         flight/PiOS/Common \
         flight/PiOS/STMF* \
         flight/PiOS.posix/posix/ \
         flight/PiOS.posix/inc \
         flight/PiOS.osx/osx/ \
         flight/PiOS.osx/inc/ ; do \
  find $i -maxdepth 1 -type f | xargs dos2unix ; \
done
````