spike-riscv: Look for the CBFS in RAM

Change-Id: I98927a70adc45d9aca916bd985932b94287921de
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/15285
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
5 files changed