build: Add support for assembling multi-image uboot files
build: Add support for assembling multi-image uboot files

Change-Id: I7300d36cc4227ada77f1800680869037ef33c5e8

ND-3500/platform_manifest,Hybrid-Power/startsync,hagar006/platform_manifest,RR-msm7x30/platform_manifest,fallouttester/platform_manifest,pranav01/platform_manifest,knone1/platform_manifest,see4ri/lolili