update mavlink to latest master
Merge pull request #1153 from PX4/mavlinkupdate

update mavlink to latest master
param command: fix warnings
AT24C: Fix warning due to missing function prototype.
Merge branch 'master' of github.com:PX4/Firmware into warning_fixes_v5
Merge branch 'warning_fixes_v5' into sensor_drivers
Tools: skip check_submodules.sh when NUTTX_SRC is set

this avoids using submodules when a specific NuttX tree is specified