initrd: enable different DEBUG levels

* DEBUG=0: log all booting message to /tmp/log in initrd and
           start logcat in android, but no debug shell.
* DEBUG=1: except DEBUG=0 behavior, enter debug shell when android
           filesystem detected.
* DEBUG=2: except DEBUG=1 behavior, ender debug shell before
           chroot to android -- the same behavior as before if
           DEBUG is not empty.
3 files changed
tree: ace705d6014a05b85cc2a110257291758d85aa40
  1. boot/
  2. editdisklbl/
  3. initrd/
  4. install/
  5. usb/
  6. Android.mk
  7. usb_layout.conf