image: android: Support boot image v1 and v2

In new versions of Android Boot Image next fields are added to the
header (and corresponding payloads are added to the image itself):
  - v1: Recovery DTBO
  - v2: DTB

Account for these new fields in next functions:
  1. android_image_get_end(): as v1 and v2 have new payloads in the
     image, the calculation of image end address should be extended
     correspondingly; this is used e.g. by "bootm" command when booting
     the kernel from Android Boot Image
  2. android_print_contents(): new fields values in v1 and v2 should be
     printed; the result of this function can be seen e.g. in "iminfo"
     command

This commit doesn't add the means for working with new payloads in v1
and v2 images (it will be done in further commits), it only updates
existing functions w.r.t. changes in boot image v1/v2.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>