hammerhead: Fix bluetooth UART device perms

Change-Id: I19b636709b7172e66372faaa28e2b3c4c224621f
hammerhead: Optimize I/O scheduling

Inspired by bacon. We aren't suffering from slowdowns
during bootanim, anyway this is the right way to do it.

Change-Id: Icf3d9d6e52926012a4b7fdfdc1456a37ad782e71