ifdtool: Cleanup IFDv1 detection

Change https://review.coreboot.org/c/coreboot/+/54305 "util/ifdtool:
Use -p platform name to detect IFDv2 platform and chipset" made
the '-p' argument mandatory for IFDv2 platforms.

Drop the IFDv2 platform CHIPSET_C620_SERIES_LEWISBURG from IFDv1
detection.

Change-Id: If29f8718b7aa696cdc07deef4c98be9a68c66f10
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68680
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/util/ifdtool/ifdtool.c b/util/ifdtool/ifdtool.c
index 1ddb6b7..4048699 100644
--- a/util/ifdtool/ifdtool.c
+++ b/util/ifdtool/ifdtool.c
@@ -203,7 +203,6 @@
 	uint32_t iccriba = (fdb->flmap2 >> 16) & 0xff;
 	uint32_t msl = (fdb->flmap2 >> 8) & 0xff;
 	uint32_t isl = (fdb->flmap1 >> 24);
-	uint32_t nm = (fdb->flmap1 >> 8) & 0x7;
 
 	/* Rest for IFD1 chipset type */
 	if (iccriba == 0x00) {
@@ -226,8 +225,6 @@
 			return CHIPSET_8_SERIES_LYNX_POINT;
 		printf("Peculiar firmware descriptor, assuming Wildcat Point compatibility.\n");
 		return CHIPSET_9_SERIES_WILDCAT_POINT;
-	} else if (nm == 6) {
-		return CHIPSET_C620_SERIES_LEWISBURG;
 	}
 	return CHIPSET_PCH_UNKNOWN;
 }