libpayload: Add SKU ID coreboot table support

This patch adds support to read the SKU ID entry from the coreboot table
that was recently added in coreboot.

Change-Id: I1c3b375da6119a4f8e8e7e25a11644becb90f927
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/22743
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

payloads/libpayload/include/sysinfo.h

@@ -112,6 +112,7 @@ struct sysinfo_t {
 #define UNDEFINED_STRAPPING_ID (~0)
 	u32		board_id;
 	u32		ram_code;
+	u32		sku_id;
 
 	void		*wifi_calibration;
 	uint64_t	ramoops_buffer;