configs: Build test OpenSBI

Build test OpenSBI on qemu-riscv-rv64.

Change-Id: I23b9a1b06987d8d8ebb90655162ba4abce1557fa
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34691
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Hug <philipp@hug.cx>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

configs/config.emulation_qemu_riscv_rv64

@@ -0,0 +1,2 @@
+CONFIG_BOARD_EMULATION_QEMU_RISCV_RV64=y
+CONFIG_RISCV_OPENSBI=y