platform: Add riscv to known platforms

Change-Id: I724a99e2493fcbf71c2fc2d9f6a1ad607c737087
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Reviewed-on: https://review.coreboot.org/25260
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
1 file changed