allow 0x34 as ICCRIBA for CHIPSET_C620_SERIES_LEWISBURG

Intel C621A Lewisburg PCH belongs to C620 series, it has 0x34 as ICCRIBA.

Fix guess_ich_chipset_from_content() accordingly.

Print status info of read_ich_descriptors_from_dump() to facilitate
debugging upon failure.

Tested: run flashrom successfully from OCP Yosemite V3 DeltaLake server.

Change-Id: I363aaccfb90e0a127c0f0bb0072e9e85c210b669
Signed-off-by: Jonathan Zhang <jonzhang@fb.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/44621
Original-Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71322
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/ich_descriptors.c b/ich_descriptors.c
index 120d3fe..2e9d0f8 100644
--- a/ich_descriptors.c
+++ b/ich_descriptors.c
@@ -937,9 +937,13 @@
 			return CHIPSET_C620_SERIES_LEWISBURG;
 		else
 			return CHIPSET_100_SERIES_SUNRISE_POINT;
+	} else if (content->ICCRIBA == 0x34) {
+		if (content->NM == 6)
+			return CHIPSET_C620_SERIES_LEWISBURG;
+		else
+			return CHIPSET_300_SERIES_CANNON_POINT;
 	} else {
-		if (content->ICCRIBA > 0x34)
-			msg_pwarn("Unknown firmware descriptor, assuming 300 series compatibility.\n");
+		msg_pwarn("Unknown firmware descriptor, assuming 300 series compatibility.\n");
 		return CHIPSET_300_SERIES_CANNON_POINT;
 	}
 }