Add support for Intel Emmitsburg PCH

This patch does the following:
- Add PCIe ID for Intel Emmitsburg PCH
- Based on ICH descriptor content, choose CHIPSET_C620_SERIES_LEWISBURG
  if ISL/PSL is 80.

Tested: tried on a server with Intel Emmitsburg PCH, flash update
was successful. This server, however, does not have flash chip
installed, it instead has em100 emulator connected.

Change-Id: I2a1bb7467e693d1583aa885fa0e277075edd4a3e
Signed-off-by: Jonathan Zhang <jonzhang@fb.com>
Signed-off-by: David Hendricks <ddaveh@amazon.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/54965
Original-Reviewed-by: Christian Walter <christian.walter@9elements.com>
Original-Reviewed-by: Johnny Lin <Johnny_Lin@wiwynn.com>
Original-Reviewed-by: Tim Chu <Tim.Chu@quantatw.com>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/71419
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/ich_descriptors.c b/ich_descriptors.c
index 9813836..1e975fa 100644
--- a/ich_descriptors.c
+++ b/ich_descriptors.c
@@ -936,6 +936,8 @@
 			warn_peculiar_desc("Gemini Lake");
 			return CHIPSET_GEMINI_LAKE;
 		}
+		if (content->ISL <= 80)
+			return CHIPSET_C620_SERIES_LEWISBURG;
 		warn_peculiar_desc("Ibex Peak");
 		return CHIPSET_5_SERIES_IBEX_PEAK;
 	} else if (upper->MDTBA == 0x00) {