Does IMG_CNTN_SET1_OFFSET secondary image boot (RM 6.1.6.2) work for ECSPI ("SPI") NOR boot on i.MX8MP, or only for FlexSPI NOR (and SD/eMMC)? Table 6-28 lists "SPI" and "FlexSPI NOR" as separate boot devices, and the secondary-offset valid values are stated only "for FlexSPI NOR boot."