Avoid printf after GetMemoryMap

The printf may invalidate the memory map obtained in bi_load (resulting
in a new MapKey), which then causes ExitBootServices to fail.

Some more work is still needed to address GetMemoryMap retries for other
situations that may invalidate the memory map, but this change at least
allowed me to boot on an Intel DQ77MK system.

Sponsored by:	The FreeBSD Foundation