Boot ROM on i.MX28 supports the SPI NOR. OTP eFuse configuration should not be modified I believe. There's examples of booting/working from SPI NOR posted on this site as well (see Spansion SPI NOR flash example).
I assume you mounted SPI flash on i.MX28EVK? By default, on board there's only footprint for SPI NOR flash, no chips mounted...
How did you configure the BOOT_MODE pins?