Instead of having separate log functions for NuttX and POSIX, this now
switches everything to px4_log.h and PX4_INFO/WARN/ERR/DEBUG.

Also, the call mostly used is now a static inline function instead of a
macro which lead to a big increase in flash size for STM32.

If a text editor creates hidden save files, those will get copied into
the ROMFS. This is now fixed by deleting hidden files.

Also, the there was some available potential by removing the leading
whitespace.

This removes a bunch of unneeded printfs and prevents broadcasting
packets of size 0 which just trigger a warning.

- Removed a couple of unneeded printfs.
- On POSIX it shouldn't warn if it's not a multiple of the
  block size.