riscv: Fix nezha hardcoded password attempt

Signed-off-by: Alexandre Ghiti <alexandre.ghiti@canonical.com>

live-build/auto/config

@@ -346,6 +346,7 @@ fi
 if [ "$IMAGEFORMAT" = "ext4" ] && [ "$PROJECT" = "ubuntu-cpc" ]; then
 	case $ARCH:$SUBARCH in
 		armhf:raspi2|riscv64:sifive_*|*:generic)
+		armhf:raspi2|riscv64:sifive_*|riscv64:nezha|*:generic)
 			IMAGE_HAS_HARDCODED_PASSWORD=1
 			if [ -z "${IMAGE_TARGETS:-}" ]; then
 				export IMAGE_TARGETS="disk1-img-xz"