This is already added to the global list, and we already removed this
flag previously, but some of them sneaked back in.

2. Remove printf in the cpp

Add -D__DF_RPI in posix_rpi_common.cmake
Add rpi_rc_in and rpi_pca9685_pwm_out  driver in posix_rpi_common.cmake
Rename posix_rpi_cross_without_navio_or_pxfmini to posix_rpi_cross_no_shield.cmake

2. Rewrite and rebase pca9685 driver
3. Try to fix issue when push the stick of channel 3 to the maxmum position, 0uswill be output to channel 1, should be maxmum pwm signal
4. Fix the code style

Now I've fixed style of the code

Both 8 channels PPM encoder and 8 channels revicer are required.
Before launch px4, ppmdeocde programe should be launched.
To download ppmdecode programe,
visit https://github.com/crossa/raspberry-pi-px4firmware.
Pxfmini and navio are not popular autopilot hardware in china,
I can handly to purchase it.
So that I use raspberry pi to build autopilot separately.
This dirver help us to decode ppm single to pwm and pushlish it

Just update in RAM is enough.

Use the size of each item type instead of the biggest one.

In AeroFC that runs is constrained mode it was using 7860 bytes
and now it uses 6930 bytes almost 1KB less.

Check for the broadcast systemd id to block forward of broadcast
commands.

   This change first pushes out the _reset_wait by 100 Ms.
   which is about 3 time longer then the code take to execute.

   Then it does the reset of the accel, gyro and mag and
   the ends the wait by setting _reset_wait to now+10 us.