Add Bootloader Assert

Per cyanogen, users on older bootloader/basebands are prone to
adverse behavior in respect to recent commits for the device.

Add assert to alert user to begin firmware update process manually.

Change-Id: I332a5cd81a8ecf4a28fd278d448bb1a9a6c44158
hammerhead: Remove deprecated flag

Change-Id: Id52576dd2262eca00292a90511245445dab2ae08
hammerhead: Make SYSTEM owner of cpu online files

This is required for the Settings app to online cpus
before writing to cpufreq files.

Change-Id: I63530bfcf095a0fbc432a908272bc89bb1ad89eb
Disable separated DTB build and remove dtbtool

* hammerhead uses DTB appended to zImage (zImage-dtb)

Change-Id: I938c0531130bc76a04494b13411cd95a6d960984
Signed-off-by: Vojtech Bocek <vbocek@gmail.com>

Conflicts:
	mkbootimg.mk