vendorcode/siemens: Ensure a given info block is available for a field

While searching for a field in all blocks ensure that the checked block
is available and can be used. In this way a field can be retrieved from
every block and not just the first one.

Change-Id: Idbd7656ab0664763cb065f5e817193ad1d9e0871
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/17670
Tested-by: build bot (Jenkins)
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
diff --git a/src/vendorcode/siemens/hwilib/hwilib.c b/src/vendorcode/siemens/hwilib/hwilib.c
index 18880ff..df9bd22 100644
--- a/src/vendorcode/siemens/hwilib/hwilib.c
+++ b/src/vendorcode/siemens/hwilib/hwilib.c
@@ -396,7 +396,8 @@
 		return 0;
 	/* Take the first valid block to get the parameter from */
 	do {
-		if ((param->pos[i].len) && (param->pos[i].offset)) {
+		if ((param->pos[i].len) && (param->pos[i].offset) &&
+		     (blk_ptr[param->pos[i].blk_type])) {
 			blk =  blk_ptr[param->pos[i].blk_type];
 			break;
 		}