[coreboot] How do I build Coreboot with both normal and fallback?

[Yaroslav K.]

Hello!

Coreboot's bootblock_normal.c supports booting a fallback romstage if
a normal romstage
boot fails. But you can only specify either "fallback" or "normal" in
CONFIG_CBFS_PREFIX.
So how do I build an image with both normal and fallback stages set?