BL2: Sanity check value in x0 in the entry point code
BL2: Sanity check value in x0 in the entry point code

Change-Id: Icef68e314e6ba0f3694189b57f4b1dbbea5ba255

davwan01/arm-trusted-firmware,96boards/arm-trusted-firmware,achingupta/arm-trusted-firmware,sandrine-bailleux-arm/arm-trusted-firmware,yatharth-arm/arm-trusted-firmware,yatharth-arm/arm-trusted-firmware,longsleep/arm-trusted-firmware-pine64,sandrine-bailleux/arm-trusted-firmware,robixnai/arm-trusted-firmware,ljerry/arm-trusted-firmware,jforissier/arm-trusted-firmware,Leo-Yan/arm-trusted-firmware,vikramkanigiri/arm-trusted-firmware,athoelke/arm-trusted-firmware,hzhuang1/arm-trusted-firmware,sandrine-bailleux-arm/arm-trusted-firmware,idl3r/arm-trusted-firmware,sandrine-bailleux/arm-trusted-firmware,jcastillo-arm/arm-trusted-firmware,longsleep/arm-trusted-firmware-pine64,hzhuang1/arm-trusted-firmware,mtk09422/arm-trusted-firmware,96boards/arm-trusted-firmware,athoelke/arm-trusted-firmware,idl3r/arm-trusted-firmware,Leo-Yan/arm-trusted-firmware,lsigithub/arm-trusted-firmware_public,achingupta/arm-trusted-firmware,davwan01/arm-trusted-firmware,lsigithub/arm-trusted-firmware_public,vikramkanigiri/arm-trusted-firmware,jcastillo-arm/arm-trusted-firmware,ljerry/arm-trusted-firmware,jforissier/arm-trusted-firmware,vchong/arm-trusted-firmware,mtk09422/arm-trusted-firmware,sbranden/arm-trusted-firmware,sbranden/arm-trusted-firmware,robixnai/arm-trusted-firmware,vchong/arm-trusted-firmware