Remove options that haven't deviated from defaults in the Coreboot
Kconfig, despite being saved by `make savedefconfig`. Also, add
`CONFIG_BOARD_LENOVO_THINKPAD_T440P`, which was missing from the `make
savedefconfig` output, causing Heads builds to fail. And finally, bump
`CONFIG_CBFS_SIZE` to `0x800000` (8 MiB to bytes to hexadecimal).
This value for the CBFS size is arbitrary. Originally, I had totaled the
size of all binary blobs, subtracted that from the T440p's ROM size (12
MiB), and used the remaining space as the CBFS size (~11.68 MiB).
However, this caused very long RAM initialization times (courtesy of
`cbmem -t`). And, an anecdote in
https://groups.google.com/a/chromium.org/g/chromium-os-reviews/c/lUqRrGUoEBY/m/ka7L1f2BS8gJ
suggested that this value needs to be a power of 2.
So, I picked a size I expected our Linux payload to fit into that was a
power of 2 that I also expected would leave enough space in the ROM for
the IFD, ME, GbE, and Coreboot.
Now, it takes less than a second for RAM initialization after
flashing/first boot (anecdotally, it seems the MRC needs to be
"trained?").
