[coreboot] CBMEM console to be made verbose

[Kyösti Mälkki]

Hi all

A change [1] has been approved that applys a minimum loglevel of BIOS_DEBUG
for CBMEM console. There should be miminal performance impact as it is
nothing but writes to cacheable memory.

For some platform this could cause that pre-ram console buffer runs out of
space. My opinion is that those are too verbose and some logging should be
moved to BIOS_SPEW. If you are debugging raminit you cannot rely on
readable CBMEM console anyways so I suggest against increasing the pre-ram
buffer size.

Regards,
Kyösti

[1] https://review.coreboot.org/c/coreboot/+/31370