ec/google/chromeec: add SSFC CBI support

An API is added to get SSFC value from cros EC.

BUG=b:174118027
BRANCH=octopus
TEST=check SSFC value from EC is correct compared to value in CBI

Change-Id: Ifd521514bbc2e90c789f3760b72e8326e614e2b1
Signed-off-by: Marco Chen <marcochen@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48791
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jett Rink <jettrink@google.com>
Reviewed-by: Zhuohao Lee <zhuohao@chromium.org>

src/ec/google/chromeec/ec.c

@@ -863,6 +863,11 @@ int google_chromeec_cbi_get_board_version(uint32_t *version)
 	return cbi_get_uint32(version, CBI_TAG_BOARD_VERSION);
 }
 
+int google_chromeec_cbi_get_ssfc(uint32_t *ssfc)
+{
+	return cbi_get_uint32(ssfc, CBI_TAG_SSFC);
+}
+
 static int cbi_get_string(char *buf, size_t bufsize, uint32_t tag)
 {
 	struct ec_params_get_cbi params = {

src/ec/google/chromeec/ec.h

@@ -89,6 +89,7 @@ int google_chromeec_cbi_get_oem_name(char *buf, size_t bufsize);
 /* version may be stored in CBI as a smaller integer width, but the EC code
    handles it correctly. */
 int google_chromeec_cbi_get_board_version(uint32_t *version);
+int google_chromeec_cbi_get_ssfc(uint32_t *ssfc);
 
 #define CROS_SKU_UNKNOWN	0xFFFFFFFF
 #define CROS_SKU_UNPROVISIONED	0x7FFFFFFF