init.sh: Parse boot type.

pre-recovery.sh will now write /cache/recovery/boot.sh with the argument.
init.sh is modified to compare the argument to "recovery".

This change fixes cases like "adb reboot bootloader" always booting recovery
afterwards.

Change-Id: Ie4cadd19641f0d2b0af6a202e9e867f0b011c5f6
msm7x30: Remove the need of specialized init binary.

Change-Id: Id41ff8808b97db772143f98753871015784f48d0
msm7x30: Move pre-recovery.sh to /sbin.

Change-Id: I2cad72ced86c79edb98e96030759f48451b8f2bd