cmd/sbi: error message for failure to get spec version

If calling 'Get SBI specification version' fails, write an error message
and return CMD_RET_FAILURE.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/cmd/riscv/sbi.c b/cmd/riscv/sbi.c
index 9bbe7d4..24955d2 100644
--- a/cmd/riscv/sbi.c
+++ b/cmd/riscv/sbi.c
@@ -56,8 +56,11 @@
 	long mvendorid, marchid, mimpid;
 
 	ret = sbi_get_spec_version();
-	if (ret >= 0)
-		printf("SBI %ld.%ld", ret >> 24, ret & 0xffffff);
+	if (ret < 0) {
+		printf("No SBI 0.2+\n");
+		return CMD_RET_FAILURE;
+	}
+	printf("SBI %ld.%ld", ret >> 24, ret & 0xffffff);
 	impl_id = sbi_get_impl_id();
 	if (impl_id >= 0) {
 		for (i = 0; i < ARRAY_SIZE(implementations); ++i) {