mb/lenovo/x220: Allow optional use of the mrc.bin

Besides the FSP codepath, Sandy Bridge has two codepaths, one native
and one in the form of a binary. This allows the use of the binary.

This can be useful to find flaws in the native raminit.

The native raminit is still selected by default.

Change-Id: I2d71fb7bc5f7b0976157be146c0e4c39a3ed5602
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/23489
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
2 files changed