i found that with libre mrc, usb was broken in grub

however, it worked nicely in seabios

for our purposes, doing seabios-only roms in text mode
is best for now

i'm going to re-add mrc.bin, but for t440p_12mb_mrc
and w541_12mb_mrc, as new config names. the regular
t440p_12mb and w541_12mb will continue to use libre
mrc, but the _mrc ones will use mrc.bin and retain the
grub payload in board.cfg

courtesy of Angel Pons from the coreboot project

this uses the following patch set from gerrit, as yet
unmerged (in coreboot master) on this date:

    https://review.coreboot.org/c/coreboot/+/64198/5

logic for downloading mrc blobs has been deleted from
lbmk, as this is now completely obsolete (for haswell
boards)

if other platforms are added later that need mrc.bin,
then logic will be re-added again for that

using the same method as the previous patch for t440p

osboot is now part of libreboot, and will soon shut down.
libreboot now conforms to osboot policy.