init.sh: parse boot type
rebased from https://github.com/LegacyXperia/android_device_semc_msm7x30-common/commit/01b4c9271831c8eb86f0b993afb606eab8a3a99b

Change-Id: Ie8f5751f90baa1ca0c8303e659402139ebd4c2e3