image: add support for Android's boot image format

image: add support for Android's boot image format

This patch adds support for the Android boot-image format. The header
file is from the Android project and got slightly alterted so the struct +
its defines are not generic but have something like a namespace. The
header file is from bootloader/legacy/include/boot/bootimg.h. The header
parsing has been written from scratch and I looked at
bootloader/legacy/usbloader/usbloader.c for some details.
The image contains the physical address (load address) of the kernel and
ramdisk. This address is considered only for the kernel image.
The "second image" defined in the image header is currently not
supported. I haven't found anything that is creating this.

v3 (Rob Herring):
This is based on http://patchwork.ozlabs.org/patch/126797/ with the
following changes:
- Rebased to current mainline
- Moved android image handling to separate functions in
  common/image-android.c
- s/u8/char/ in header to fix string function warnings
- Use SPDX identifiers for licenses
- Cleaned-up file source information:
  android_image.h is from file include/boot/bootimg.h in repository:
  https://android.googlesource.com/platform/bootable/bootloader/legacy
  The git commit hash is 4205b865141ff2e255fe1d3bd16de18e217ef06a
  usbloader.c would be from the same commit, but it does not appear
  to have been used for any actual code.
v4:
- s/andriod/android/
- Use a separate flag ep_found to track if the entry point has been set
rather than using a magic value.

Cc: Wolfgang Denk <wd@denx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Tom Rini <trini@ti.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>