meta-android: kernel_android: implement kernel update

* when the kernel package is installed or updated the kernel fastboot image is now flashed
  to the device boot partition

Signed-off-by: Simon Busch <morphis@gravedo.de>
meta-samsung: linux-samsung-tuna: specify boot partition for kernel update

Signed-off-by: Simon Busch <morphis@gravedo.de>
meta-asus: linux-asus-grouper: specify boot partition for kernel update

Signed-off-by: Simon Busch <morphis@gravedo.de>