Pull more PX4-specific code from the NuttX tree.
cdcacm: fixed SELFPOWERED and REMOTEWAKEUP bits in USB attributes

the ifndef checks should be ifdef. This was causing the wrong
attributes on USB, which could limit available power on some host
systems
Merge pull request #4 from PX4/kconfig-cleanup

Pull more PX4-specific code from the NuttX tree.
Fix handling of filenames > 15 characters in ROMFS.