riscv: qemu: enable distro boot from scsi

Booting via distro boot fails for:

    qemu-system-riscv64
    -drive if=none,file=sct-riscv64.img,format=raw,id=mydisk \
    -device ich9-ahci,id=ahci -device ide-hd,drive=mydisk,bus=ahci.0

Enable distro booting from an attached SCSI disk.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Bin Meng <bin.meng@windriver.com>

include/configs/qemu-riscv.h

@@ -35,6 +35,7 @@
 #define BOOT_TARGET_DEVICES(func) \
 	func(QEMU, qemu, na) \
 	func(VIRTIO, virtio, 0) \
+	func(SCSI, scsi, 0) \
 	func(DHCP, dhcp, na)
 
 #include <config_distro_bootcmd.h>