libbpf: Propagate errors when retrieving enum value for typed data display

When retrieving the enum value associated with typed data during
"is data zero?" checking in btf_dump_type_data_check_zero(), the
return value of btf_dump_get_enum_value() is not passed to the caller
if the function returns a non-zero (error) value.  Currently, 0
is returned if the function returns an error.  We should instead
propagate the error to the caller.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1626770993-11073-4-git-send-email-alan.maguire@oracle.com

tools/lib/bpf/btf_dump.c

@@ -2166,8 +2166,9 @@ static int btf_dump_type_data_check_zero(struct btf_dump *d,
 		return -ENODATA;
 	}
 	case BTF_KIND_ENUM:
-		if (btf_dump_get_enum_value(d, t, data, id, &value))
-			return 0;
+		err = btf_dump_get_enum_value(d, t, data, id, &value);
+		if (err)
+			return err;
 		if (value == 0)
 			return -ENODATA;
 		return 0;