omap4-hijack: unbreak logwrapper on stock

Change-Id: I24d0f3ff5693d168363f15ce21b9e775f15f2bf9
motorola/omap4: use kexec for recovery-kernel

Use kexec to boot a custom kernel for TWRP instead of running
it on the stock kernel. This adds SELinux-support to the
recovery.

Change-Id: I4bc3987b6d703adecb4305159b80425ae3c6df46