chromeec: make ssfc optional in fw_config

When EC_GOOGLE_CHROMEEC_INCLUDE_SSFC_IN_FW_CONFIG is enabled and SSFC is
not set, all fw_config is invalidated. But for some platform this may
not be necessary, we can treat missing SSFC as zero and use other 32
bits of firmware config.

BUG=b:184809649
TEST=boot and check fw_config is not -1 even if ssfc is not set
BRANCH=zork

Signed-off-by: Kangheui Won <khwon@chromium.org>
Change-Id: I21c7b0d449a694d28ad7b3f14b035e3a5830030a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52205
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Marco Chen <marcochen@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
diff --git a/src/ec/google/chromeec/ec.c b/src/ec/google/chromeec/ec.c
index affe66e..29d0411 100644
--- a/src/ec/google/chromeec/ec.c
+++ b/src/ec/google/chromeec/ec.c
@@ -856,10 +856,8 @@
 	if (CONFIG(EC_GOOGLE_CHROMEEC_INCLUDE_SSFC_IN_FW_CONFIG)) {
 		uint32_t ssfc;
 
-		if (google_chromeec_cbi_get_ssfc(&ssfc))
-			return -1;
-
-		*fw_config |= (uint64_t)ssfc << 32;
+		if (!google_chromeec_cbi_get_ssfc(&ssfc))
+			*fw_config |= (uint64_t)ssfc << 32;
 	}
 	return 0;
 }