ec/google/chromeec: add smbios_mainboard_manufacturer()

When EC_GOOGLE_CHROMEEC_SKUID is selected provide an
implementation of smbios_mainboard_manufacturer() so the code
doesn't need to be duplicated in the mainboards.

BUG=b:153767369

Change-Id: Ib65fe373a79d606cffcba71882b0db61be5a18c3
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40317
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/ec/google/chromeec/ec_skuid.c

@@ -37,3 +37,22 @@ const char *smbios_system_sku(void)
 {
 	return google_chromeec_smbios_system_sku();
 }
+
+const char *smbios_mainboard_manufacturer(void)
+{
+	static char oem_name[32];
+	static const char *manuf;
+
+	if (manuf)
+		return manuf;
+
+	if (google_chromeec_cbi_get_oem_name(&oem_name[0],
+			ARRAY_SIZE(oem_name)) < 0) {
+		printk(BIOS_ERR, "Couldn't obtain OEM name from CBI\n");
+		manuf = CONFIG_MAINBOARD_SMBIOS_MANUFACTURER;
+	} else {
+		manuf = &oem_name[0];
+	}
+
+	return manuf;
+}