Some Davinci processors supports the Application
Image Script (AIS) boot process. The patch adds the generation
of the AIS image inside the mkimage tool to make possible
to generate a bootable U-boot without external tools
(TI Davinci AIS Generator).

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Wolfgang Denk <wd@denx.de>