riscv: Add initial support for 32bit boards

* Adding separate targets for 32bit and 64bit qemu
* Using the riscv64 toolchain for 32bit builds requires setting -m elf32lriscv
* rv32/rv64 is currently configured with ARCH_RISCV_RV32/RV64 and not per stage.
  This should probably be changed later.

TEST=Boots to "Payload not loaded." on 32bit qemu using the following commands:

util/riscv/make-spike-elf.sh build/coreboot.rom build/coreboot.elf
qemu-system-riscv32 -M virt -m 1024M -nographic -kernel build/coreboot.elf

Change-Id: I35e59b459d1770df10b51fe9e77dcc474d7c75a0
Signed-off-by: Philipp Hug <philipp@hug.cx>
Reviewed-on: https://review.coreboot.org/c/31253
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: ron minnich <rminnich@gmail.com>

0 files changed, 0 insertions, 0 deletions