arch/riscv: Implement the SBI again

Not all SBI calls are implemented, but it's enough to see a couple dozen
lines of Linux boot output.

It should also be noted that the SBI is still in flux:
https://groups.google.com/a/groups.riscv.org/forum/#!topic/sw-dev/6oNhlW0OFKM

Change-Id: I80e4fe508336d6428ca7136bc388fbc3cda4f1e4
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/16119
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

0 files changed, 0 insertions, 0 deletions