bloblist: kconfig for mandatory incoming standard passage

In previous commit, incoming standard passage is used by default
when initializing the bloblist, so explicitly BLOBLIST_PASSAGE is
no more needed.
Rename it as BLOBLIST_PASSAGE_MANDATORY to determine the behaviors
when an incoming transfer list does not exist or is invalid.
When it is selected, incoming standard passage is mandatory and
U-Boot will report an error when a valid incoming transfer list is
missing.

Signed-off-by: Raymond Mao <raymond.mao@linaro.org>
diff --git a/common/bloblist.c b/common/bloblist.c
index be05f80..fb0e5af 100644
--- a/common/bloblist.c
+++ b/common/bloblist.c
@@ -513,6 +513,13 @@
 		 */
 		bool from_addr = fixed && !xpl_is_first_phase();
 
+		/*
+		 * If Firmware Handoff is mandatory but no transfer list is
+		 * observed, report it as an error.
+		 */
+		if (IS_ENABLED(CONFIG_BLOBLIST_PASSAGE_MANDATORY))
+			return -ENOENT;
+
 		ret = -ENOENT;
 
 		if (xpl_prev_phase() == PHASE_TPL &&