The MRC cache wants to be able to access the SPI flash boot device.
Allow an easy way to provide that so that there isn't duplicate
spi_flash objects representing the same device.
BUG=chrome-os-partner:56151
Change-Id: Iba92e8bb8a6060cdd327b10f5f8ec23ac61101e7
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/17715
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>