Android: bootm: Add boot with Android boot image

Android boot image is consisted with kernel and ramdisk image, details of each
images are specified in its header when created. This patch is to load single
Android boot image when detected, and relocate individual images into specified
address, then recall the command 'bootm' with new addresses. Therefore, Android
boot image must loaded in different area from each images, not to be overlaped
while being relocated.

Signed-off-by: Dongjin Kim <dongjin.kim@agreeyamobility.net>