Nyan-big RCM mode

Acer Chromebook 13 aka Nyan-Big RCM mode

freenode #tegra log

< paulk-collins> zombah, the rcm usb port is the back one
< paulk-collins> as for triggering that mode, it's probably not very easy
< paulk-collins> zombah, there's a pin you need to ground
< paulk-collins> zombah, it's on JP9
< tagr> paulk-collins, zombah: depending on your userspace and/or kernel you can run "reboot forced-recovery" to get into RCM