ichspi: Disable software sequencing by default for Skylake

Skylake is a mess, especially with coreboot. We have now a present and
configured software sequencing interface with SCGO supposedly being
readonly (Apollo Lake has that feature and a strap documented, Skylake
behaviour might be the same). As we can't easily check if it's read-
only, just enable hardware sequencing by default (even if the software
sequencing interface seems usable).

Change-Id: I8a13fb9c3ca679b3f7d39ad1dc56d5efdc80045b
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/22274
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
diff --git a/ichspi.c b/ichspi.c
index ec81628..859d55f 100644
--- a/ichspi.c
+++ b/ichspi.c
@@ -1951,6 +1951,11 @@
 			ich_spi_mode = ich_hwseq;
 		}
 
+		if (ich_spi_mode == ich_auto && ich_gen == CHIPSET_100_SERIES_SUNRISE_POINT) {
+			msg_pdbg("Enabling hardware sequencing by default for 100 series PCH.\n");
+			ich_spi_mode = ich_hwseq;
+		}
+
 		if (ich_spi_mode == ich_hwseq) {
 			if (!desc_valid) {
 				msg_perr("Hardware sequencing was requested "